Small Basic continues the tradition of BASIC programming. . Subroutines may be defined within programs, or separately in libraries that can be used by many programs. But the main program knows about it (for example, it can display the variable). The entire city will be under the attack of the merciless, ferocious dragon. The statements that make up the subroutine are sandwiched between the Sub and EndSub keywords (lines 1114). 11. Ends the function definition. Write a subroutine named MumGluffToFoot() that converts mum-gluffs to feet. And it doesnt define subroutines that directly return a value (like the Math.Round() method does). The conversion to a UWP app also seems to be more of a political move than a technical necessity and not being able to use extensions makes it dead in the water. See the online resources to learn more. line size. This is where you define the function, earlier you declared the function. Otherwise, the ghost tries to find the user (by selecting a room number at random). The first is that methods attached to supplied objects do have parameters. This is the number of steps Good Knight has to take to get to Draggy. Dear Learners,I am Rhea Agrawal, and I welcome you to Erudemy Learning. In this game, you control the knight, and its your job to slay the dragon. As the programmer, youre the manager, and your job is to solve problems as you build your program. To do this, add the NewGame() subroutine in Listing 10-9 to your program. There are currently extensions which allow you to create Windows Forms, do math , use a Joystick and so on. We recommend you follow the same practice in your own programs: itll help keep you organized! "),d=t;a[0]in d||!d.execScript||d.execScript("var "+a[0]);for(var e;a.length&&(e=a.shift());)a.length||void 0===c?d[e]?d=d[e]:d=d[e]={}:d[e]=c};function v(b){var c=b.length;if(0 The card is blank. These can be written in any .NET language and they are very easy to create. In this case, you check the shields strength (line 10); if its 0, the game is over (lines 1112). If the number is 1 (line 2), the knight hits the dragon and the game ends (lines 34). Lets think about the moveStep line a little. The user simply has to learn about the new object and what it can do for them. Small Basic does have a place in the world of educational languages but you need to keep in mind that it isn't open source and Microsoft seems keen to keep it under their control - its only for educational use. When you have a good idea of the problem you need to solve, plan a general solution. Next, youll add the Pick() subroutine in Listing 10-5 to the bottom of your program. That is if you want to write an Add subroutine you can: but a and b have to exist within the program before the subroutine is called and c will be created as a global variable by the subroutine, assuming it doesn't already exist. This is how the statement on line 15 works: if player is 1 (you, the user), then 3 1 is 2 (switching to the computers turn), and if player is 2 (the computer), then 3 2 is 1 (switching back to the users turn). That is, the function-name acts like a variable and it is the functions returned value. When you need to perform a job that a subroutine handles, you just call that subroutine and wait. This was the beginning of this project. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. The result line its must not exceed the max. If the player picks the card with the jalapeo, the player has to eat a hot pepper and the computer wins! You then move the knights image to the left (line 5). SOLVING PROBLEMS WITH SUBROUTINES - This book introduces you to Small Basic in a fun, engaging, and interactive way. On functions you must use the functions name to return the value. A desktop version of 1.3 is promised for some time in the future but there is no sign of it more than six months after the launch. Every time the user goes to the shop, the program will go back to the Shops Subroutine, and if the user bought an item, it would call a "Buy Item" function. Follow Listing 10-3 and note how we put the code for calculating the triangles area (Herons formula) in a subroutine. When the subroutine completes its task, you move on to the next step in your program. If the user chooses to shoot an arrow but doesnt have any arrows, you tell them theyre out of arrows and ask them again (lines 1417). If you run the game now, you should see all the images and numbers in place, but nothing will happen yet. An approach known as structured programming started in the mid-1960s to simplify the process of writing, understanding, and maintaining computer programs. 2. Sections names are used at limited OSes like PalmOS for multiple 32kB source code sections. Otherwise, the choice the user makes is acceptable. The generic p= operators are used as in C Where p any character of -+/\*^%&|, All these pseudo-operators are not allowed inside of expressions. That means the data-type is invisible to user. In short you better prepare a good answer to "why use a subroutine when all the variables are global.". A usual problem is that name may be used again in a function or procedure. After this point, if the dragons fire hits the knight, itll burninate him! As a manager, you dont have to know all the nitty-gritty details of building a home: the plumber handles the plumbing, the roofer shingles the roof, and the electrician runs all the wires. This subroutine is pretty basic (and small!). The symbol $ is supported for compatibility. You wait 1 second (line 5) and switch the images back (lines 67). This does seem to be the right way to do things. Find out more about the Microsoft MVP Award Program. In this book, well start the name of a subroutine with a capital letter. To call a subroutine, you type its name followed by parentheses (line 5). Too bad you can't train dragons. A subroutine is a collection of statements that do a specific job (just like hiring Mario the plumber to build a fancy toilet). Otherwise, the ghost moves to a different room, and the user tries again. You dont have to write the same code over and over again! Take a look at them and get an understanding of the use of Goto statement. The subroutine runs, saves its output(s) in some variables, and returns to the main program. If the ghost finds the user, the game ends. You can use the symbol @ instead of BYREF. The parameters are by value by default. 8 EndIf 910 TextWindow.Write("[Press any key]")11 TextWindow.PauseWithoutMessage()12 TextWindow.WriteLine("")1314 card = Math.GetRandomNumber(10) ' Picks a random card15 Animate() ' Animates the delay in picking a card16 EndSub, Listing 10-5: The Pick() subroutine for Pepper Dare. For example: b[10]=3test["data"]=bb[10]=4TextWindow.WriteLine( test["data"][10]). If the knight misses, you tell the knight that he missed (line 6), delay the program for your user to read the message (line 7), and return to the ProcessChoice()subroutine. Now add the Animate() subroutine in Listing 10-6 to the bottom of your program. Read the content on the left for the need of subroutines in a program. Step 5: Get the Player in the Game with GetChoice(). Wait for the user to press enter (So you can read the output with out it flashing away in a second). Otherwise, you tell Good Knight that his arrow missed (line 20), delay the program for your user to read the message (line 21), and return to the ProcessChoice() subroutine, which returns to the main program to give the dragon his turn. A value of 1 means the dragon has hit the knight (line 9). Passing parameters by reference means the executor push the pointer of variable into the stack. 3. salesTax is the function identifier or its name, and in parentheses are the parameters (If you have more than one parameter, separate them with a comma). You taste like chicken.") You randomly pick the number 1 or 2. These are worrying times for Small Basic users. There is hardly a difference between the two, except that a function returns a value, where a subroutine just repeats lines of code (A function is not always used more than once). Then have your main program call DrawHead(), DrawEyes(), DrawMouths(), and DrawBody() to draw the alien! The width of the background image is 480 pixels. Youll learn about it in depth in Chapter 13. SmallBASIC includes trigonometric, matrices and algebra functions, a built in IDE, a powerful string library, system, sound, and graphic commands along with structured programming syntax. Use the LOCAL keyword for local variables. In that example, every element of V() will be trimmed. (e in b.c))if(0>=c.offsetWidth&&0>=c.offsetHeight)a=!1;else{d=c.getBoundingClientRect();var f=document.body;a=d.top+("pageYOffset"in window?window.pageYOffset:(document.documentElement||f.parentNode||f).scrollTop);d=d.left+("pageXOffset"in window?window.pageXOffset:(document.documentElement||f.parentNode||f).scrollLeft);f=a.toString()+","+d;b.b.hasOwnProperty(f)?a=!1:(b.b[f]=!0,a=a<=b.g.height&&d<=b.g.width)}a&&(b.a.push(e),b.c[e]=!0)}y.prototype.checkImageForCriticality=function(b){b.getBoundingClientRect&&z(this,b)};u("pagespeed.CriticalImages.checkImageForCriticality",function(b){x.checkImageForCriticality(b)});u("pagespeed.CriticalImages.checkCriticalImages",function(){A(x)});function A(b){b.b={};for(var c=["IMG","INPUT"],a=[],d=0;d, Figure 10-1: Subroutines are the building blocks of larger programs. [Press any key]---------> Hot tamale, it's a pepper! Use the force! Some programs have the same subroutines. This makes your code easier to read and maintain. Ignore the line numbers; they are used for explaining the code. If your user enters any number other than 1, 2, or 3, you ask them to enter a number again (lines 1012). 1. GraphicsWindow.MouseMove=MyEventHandlerSub MyEventHandlerx=GraphicsWindow.MouseXy=GraphicsWindow.MouseYand so onEndSub. This keyword is used to declare single-line commands. When the game starts, the player is handed 10 imaginary cards face down. The previous example showed you how subroutines can add structure and clarity to your programs. Instead of writing a single, large program, you divide your program into smaller pieces. 1 ' GlumGluff.sb2 TextWindow.Write("How many glum-gluffs? This code contains all the one-time setup for your game; its a little long, but well talk you through it. If the random number is 2 (line 18), you tell the knight that the dragons fire missed him (line 19) and return to the main program. Step 4: Let the Player Know Whats Going On. Because your subroutines can change variables that belong to the main program, be sure to name your variables carefully and clearly. You pick a random number thats either a 1 or a 2. Then the code goes into a loop (lines 814) to manage the game. When the user presses any key, the Pause() method ends, and you call the End() method to exit your program (line 3). To find out how the sizes of items in Lilliput compare to sizes in our land, write the program in Listing 10-1, which converts glum-gluffs to inches. BASIC Programming/Subroutines and Functions, Last edited on 10 September 2022, at 05:04, https://en.wikibooks.org/w/index.php?title=BASIC_Programming/Subroutines_and_Functions&oldid=4103989. 9 GameOver()10 EndIf11 EndSub, Listing 10-13: The subroutine that moves Good Knight. Small Basic's biggest problem is the fact that it not only has labels and the Goto but the introductory documentation makes use of this facility. Youll add the subroutines in a moment. The default is zero. 1 Sub ShootArrow 2 arrows = arrows - 1 3 Shapes.SetText(arrowsText, arrows) 4 5 range = Math.GetRandomNumber(dist) 6 7 ' Animates the arrow 8 pos1X = 100 + dist * moveStep 9 pos2X = 100 + (dist - range)* moveStep10 Shapes.Move(arrowImg, pos1X, 280)11 Shapes.ShowShape(arrowImg)12 Shapes.Animate(arrowImg, pos2X, 280, 2000)13 Program.Delay(2000)14 Shapes.HideShape(arrowImg)1516 If (range = dist) Then ' You hit the dragon right on17 Shapes.SetText(msgText, "Perfect shot. If the knight didnt kill Draggy and end the game, the main program calls DragonFire() to give the dragon a fair fight. The function would ask for a subtotal, take that number and multiply it by 1.07 (If sales tax is 7%, the 1 is because you are adding onto the subtotal to make a total, not finding the sales tax itself). (function(){for(var g="function"==typeof Object.defineProperties?Object.defineProperty:function(b,c,a){if(a.get||a.set)throw new TypeError("ES3 does not support getters and setters. 10. In computer programming, a subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. Example: (Clie HiRes), TEXTMODE Sets the text mode flag (-g- option), CSTR Sets as default string style the C-style special character encoding (\), ANTIALIAS off : Disable anti-aliasing for drawing commands like CIRCEL or LINE, Used by Unix to make source runs as a script executable. If you've already registered, sign in. IN operator is used to compare if the left-value belongs to right-value. Variable names can use any alphanumeric characters, extended characters (ASCII codes 128-255 for non-English languages) the symbol _, and the symbol$. Next, lets rewrite this program and put the conversion statements (lines 56) in a subroutine named GlumGluffToInch(). Each round, you ask the knight for his next move (line 9), process his move by calling ProcessChoice() on line 11, and then give the dragon a turn (line 13). Youll add the code for these subroutines one step at a time. That is you can use: This makes the Small Basic array a much more powerful data structure than it first appears to be. Add the ShootArrow() subroutine in Listing 10-15 to make the Good Knight a master archer who puts Hawkeye to shame. For example, if the s variable seems confusing, rename it to semiperimeter so youll remember what it does. Follow steps 110 to make a fun dragon game! Figure 10-4: Calculating the area of the piece of land you inherited. You inherited some land (Figure 10-4) from Uncle Moneybags. Asynchronous programming is the norm not the exception and the fact that Small Basic has such a simple and easy to use implementation is a huge plus. In that example the destination is the LEN(FILES("*.txt"))-1 For each value of i the destination will be evaluated. Heres a sample run of the completed Pepper Dare program: Your turn. So every time Good Knight moves forward, well move his image to the left by 280 / dist pixels. The main program now doesnt have to worry about how the conversion is done. Run the program to figure out how tall the king is in inches; remember that hes 8.5 glum-gluffs tall. A quick explanation for digital technology students at Bellarine Secondary College. Thats very similar to how subroutines work! (e in b)&&0=b[e].o&&a.height>=b[e].m)&&(b[e]={rw:a.width,rh:a.height,ow:a.naturalWidth,oh:a.naturalHeight})}return b}var C="";u("pagespeed.CriticalImages.getBeaconData",function(){return C});u("pagespeed.CriticalImages.Run",function(b,c,a,d,e,f){var r=new y(b,c,a,e,f);x=r;d&&w(function(){window.setTimeout(function(){A(r)},0)})});})();pagespeed.CriticalImages.Run('/mod_pagespeed_beacon','https://apprize.best/programming/basic/12.html','2L-ZMDIrHf',true,false,'ijtKnN8avuQ'); ")10 TextWindow.WriteLine("")11 Else12 TextWindow.Write("The card is blank. ")3 glumGluffs = TextWindow.ReadNumber()45 inches = 0.75 * glumGluffs ' Converts to inches6 inches = Math.Round(inches * 100) / 100 ' Rounds to 2 decimal places7 TextWindow.WriteLine("That's about " + inches + " inches."). In Figure 10-6, the main program calls a subroutine, SubA(), which then calls another subroutine, SubC(). I created a forum thread for the purpose. On the screen you can see which variables well display to keep score and where the player makes a choice of three actions to play. The first character of the name cannot be a digit nor$. ")14 TextWindow.WriteLine("")15 player = 3 - player ' Switches the player16 Goto Again17 EndIf. This is actually a macro for compatibility with the BASICs DEF FN command, but quite useful. (ex. If the player doesnt get the pepper card, the computer takes a turn. After the subroutine call, the main program stores this first area in thetotalArea variable (line 7). 9 TextWindow.WriteLine(name + " wins! The 10th tutorial in the Small Basic Beginner Level series! You clear the message text in line 24, add an empty line to the text window in line 25 to prepare for the next prompt, and return to the main program (line 26). How about using GitHub Gist to use my subroutines or your own subroutines? 1 Sub Animate2 For N = 1 To card3 TextWindow.Write("-")4 Program.Delay(100)5 EndFor6 TextWindow.Write("-> ")7 EndSub, Listing 10-6: Subroutine to animate the delay. 1 Sub UpdateUserInterface2 Shapes.SetText(distText, dist)3 Shapes.SetText(arrowsText, arrows)4 Shapes.SetText(shieldText, shield)5 EndSub, Listing 10-10: Subroutine that updates the text. You can't use parameters in a user defined subroutine. After you set the games parameters, youll need to show them to the user. All of these events occur within the GraphicsWindow object which is a more advanced version of the TextWindow. You set the titles for the graphics and text windows (lines 23). The simple answer goes back to the observation that all variables are global and in scope within every subroutine. Then you load and position the images for the knight, dragon, and arrow (lines 2935). Recall that we saved these identifiers when we created these text shapes in the SetUp() subroutine (lines 1921 in Listing 10-8). The game then switches to the next player (line 15) and goes back to start a new round (line 16). The philosophy of Small Basic is to keep it simple and to resist the temptation to expand the language to the point where it becomes too complex for the beginner. To access a member of a unit we must use the unit-name, a point and the name of the member. Subroutines called from other subroutines are nested subroutines. If the arrow hits the dragon, itll slay him instantly! or [^SET] matches any character not in the specified set. But you need to know the area of the land before you can sell it. 1 ' GlumGluff2.sb 2 TextWindow.Write("How many glum-gluffs? ") Code Branches and Subroutines In this lesson, you will learn how to: Branch your code using the If Else EndIf key words; If you happen to have a Kinect handy then this does provides the opportunity for some interesting projects. But there is an option to use PCRE (Perl-Compatible Regular Expression library) on systems that is supported (Linux); (see OPTION). Units are a set of procedures, functions and/or variables that can be used by another SB program or SB unit. As a UWP app it will only run on Windows 10 and its use is controlled - you can only install it on a maximum of 10 Windows machines. As the solution planner, you decide what those tasks are. Small Basic Subroutine Library Project. Display the subtotal. Copyright 2009-2022 i-programmer.info. This is a very simple approach to subroutines and it closely follows the early Basic Gosub construct which also didn't have parameters or return values. The value in callers code will not be changed. Pseudo operators. If you avoid mentioning that it exists and help your student to learn how to put the flow of control together without it then it is a good introduction. 1 Sub GetChoice 2 AskAgain: 3 TextWindow.WriteLine("Select:") 4 TextWindow.WriteLine(" [1] Move 1 step forward") 5 TextWindow.WriteLine(" [2] Shoot an arrow") 6 TextWindow.WriteLine(" [3] Stab the dragon (you have to be 1 step away)") 7 TextWindow.Write(" Your choice [1-3]: ") 8 9 choice = TextWindow.ReadNumber()10 If((choice <> 1) And (choice <> 2) And (choice <> 3)) Then11 Goto AskAgain12 EndIf1314 If ((choice = 2) And (arrows = 0)) Then15 Shapes.SetText(msgText, "You ran out of arrows! Then it randomly picks a card (line 14) and calls the nested Animate()subroutine to animate an arrow in the text window. ");b!=Array.prototype&&b!=Object.prototype&&(b[c]=a.value)},h="undefined"!=typeof window&&window===this?this:"undefined"!=typeof global&&null!=global?global:this,k=["String","prototype","repeat"],l=0;lb||1342177279>>=1)c+=c;return a};q!=p&&null!=q&&g(h,n,{configurable:!0,writable:!0,value:q});var t=this;function u(b,c){var a=b.split(". Subroutines are like methods, but you have to write all the statements in the subroutines. The knight makes the first move. You then move the arrow to its start position (line 10), show it (line 11), animate it to its final position (line 12), wait for it to reach its target (line 13), and then hide it (line 14). !^-\\', and match the character exactly, precede it with a\. These operators are replaced by compiler with a command or an expression. That is an array cannot contain a reference to another data structure. Use the x variable to specify the parameter of the expression. To understand how this works, lets assume that the knights initial distance from the dragon, dist, is 10, which makes moveStep = 28, as illustrated in Figure 10-7. SmallBASIC includes trigonometric, matrices and algebra functions, a built in IDE, a powerful string library, system, sound, and graphic commands along with structured programming syntax. But if you put those statements in a subroutine, you can call it from any point in your program (code reuse). If the picked card has a pepper on it (line 7), the game displays the winners name (line 9), and the game ends because the program moves out of the If loop and jumps from line 10 to line 17, bypassing the Goto loop on line 16. That is you can't define a subroutine like: You isolate (or separate) the unit conversion details from the main program. But the same functional subroutines became different versions. Youll likely need to do that when designing your own UIs for your awesome future games. The functions, procedure or variables which we want to be visible to another programs must be declared with the EXPORT keyword. The same code is used for filenames (FILES(), DIRWALK) too. It can be used with WHILE and FOR-family commands. Small Basic Sample: The Triangle Area Calculator Nesting Subroutines Overview A subroutine might call other subroutines, like in Figure 1. Small Basic confronts this task head on and it is simple enough and rewarding enough to work. It has some improvements but the fact that it no longer works with extensions makes it incompatible with a very large number of existing Small Basic programs. Array (~2970 elements on 16bit / ~50M elements on 32bit), XMAX Graphics display, maximum x (width-1), YMAX Graphics display, maximum y (height-1) value. // The card is blank. Raspberry Pi or Programming - What shall we teach the children? The only data structures that Small Basic has are the string, which is supported via a Text object for string manipulation and a one or two dimensional array. Where p any character of -+/\*^%&, Separates commands typed on the same line. After drawing the background image (lines 1415), you create and position the text shapes that youll use to show all the numbers on the games UI (lines 1926). This file contains the code in Listing 10-7 and has empty placeholders for your subroutines. so this makes it necessary to at least introduce parameters if only in a limited way. Parameters are used in functions and subroutines. But as you start dealing with more complex problems, youll need to write longer programs. This is what line 5 receives, the function shoots out the variable Total. This is the default data type. This line is the function's prototype. If you are the copyright holder of any material contained on our site and intend to remove it, please contact our site administrator for approval. Functions must be declared as a prototype before they are used, and must be defined after the end (of the program) statement. matches any character in the specified set. For use with our two examples: There are two different ways to send parameters: by the value or by reference. If the user finds the ghost in that room, they win! Your game is done! Then you increase the value of the j variable by 1. Robin Hood is giving lessons. Dont worry about the For loop here. Display the total. The event data, such as the mouse position, is made available to the event handler via properties on the GraphicsWindow object. Define Total2 by passing SubTotal2 as an argument(parameter) to the function salesTax (The value of Total2 will be what the function returns). There is a problem with 1 dimension arrays, because 1-dim arrays does not specify how SmallBASIC must see them. Also, there is no extra code on compiler which means that SB compiles the pattern every time it is used. Try every exercise and dig in to the extra online resources, review questions, and practice exercises. In this chapter, youll learn how to organize your programs into smaller pieces. That is WRONG but it is supported by BASIC and many other languages. After that, the dragon has a 50-50 chance to hit the knight with his fire. Understanding long programs can be a challenge, because youll need to keep track of many different parts of the program. ")16 Goto AskAgain17 EndIf1819 If ((choice = 3) And (dist > 1)) Then20 Shapes.SetText(msgText, "You're too far to use your sword. This was the beginning of this project. 1 ' PepperDare.sb 2 player = 1 ' 1 for player, 2 for computer 3 pepper = Math.GetRandomNumber(10) ' Which card has the pepper 4 5 Again: 6 Pick() ' Updates the two variables: card and name 7 If (card = pepper) Then 8 TextWindow.Write("Hot tamale, it's a pepper! ") It is compares the left part of the expression with the pattern (right part). When we place the dragon and the knight on the background, the distance from the dragons right edge to the knights left edge is 280 pixels. The subroutines name comes after the Sub keyword (line 11). Pick a card. This subroutine is in Listing 10-14; add it to your program now. A subroutine would be code that is reused, like a shop in a game. Otherwise, it displays The card is blank. Play it several times and enjoy your creation! This is called the variable scope). You put it back in and shuffle the deck. This program looks just like the ones youre already used to! The figure also shows Herons formula, which computes the area of a triangle given the lengths of its three sides. A RETURN statement in a subroutine causes GW-BASIC to return to the statement following the most recent GOSUB statement. 1 Sub ProcessChoice2 If (choice = 1) Then ' Move-forward subroutine3 MoveKnight()4 ElseIf (choice = 2) Then ' Shoot-arrow subroutine5 ShootArrow()6 Else ' Stab subroutine7 StabDragon()8 EndIf9 EndSub, Listing 10-12: Jumping to the choices subroutine. Examples: The END statement in line 30 prevents re-execution of the subroutine. This page was last edited on 10 September 2022, at 05:04. LOCAL creates variables (dynamic) at routines code. This subroutine calls Pause() to give your user a chance to read the message (line 2). A subroutine can contain more than one RETURN statement, should logic dictate a RETURN at different points in the subroutine. In the fourth line, you determine whether the value of the j variable is smaller than 10. (lines 1213) to indicate that the player (or the computer) picked a blank card. This variable isnt intended to be used by the main program, which just cares about the area variable. When the game starts, Good Knight is on the right, some distance from Draggy the dragon. Such nesting of subroutines is limited only by available memory. Similarly, a subroutine might call other subroutines to help it do part of a larger job. The function would take the new total and give it back to the program. Otherwise, register and sign in. What matters is the order in which you call these subroutines, not where you place them in your code! 1 ' Dragon_Incomplete.sb 2 SetUp() ' Does one-time set up 3 4 NewGame() ' Sets the parameters for a new game 5 6 UpdateUserInterface() ' Shows values on background image 7 8 NextMove: 9 GetChoice() ' Displays options and gets the knight's choice1011 ProcessChoice() ' Processes the user's choice1213 DragonFire() ' Now it's the dragon's turn14 Goto NextMove, Listing 10-7: High-level structure of the dragon game. When you define the subroutine, dont put parentheses after its name. When the shield loses its strength, the knight is defenseless. If they want to stab the dragon but are too far away, you tell them theyre too far away and ask them to choose again (lines 1922). Uncle Moneybags left you another piece of land (Figure 10-5)! Each subroutine does something different, just like how the plumber and the roofer have different jobs, but all are needed to build the house. In this challenge, youll develop the game Ghost Hunt (see the following figure). But if it isnt 0, you reduce the shields strength by 1 (line 14), display the new value (line 15), tell the knight that he was hit (line 16), and return to the main program. By Value means that the function can not actually change the data outside of the function, but can use its data to manipulate other data that is returned. You can change the value 2000 in lines 12 and 13 to make the animation shorter or longer. In other words, you tell the computer to display the value of the j variable, increase its value by 1, and then determine whether that value is smaller than 10. A subroutine may be called any number of times in a program, and a subroutine may be called from within another subroutine. You start by displaying the options to the user (lines 37). In this video, the basics of sub routine in small basic will be introduced to the students. Arrays are always dynamic, even if you had declared their size, with dynamic size and type of elements. But just because you define a subroutine doesnt mean your program will run it. Constant variables can be declared by using the keyword CONST. The TriangleArea() subroutine uses a temporary variable named s to store the semiperimeter, one-half of the perimeter of the current shape (line 24). It does serve to introduce the idea of modular construction but there are some problems. A subroutine can access all the variables in the main program, and the main program can access all the variables in a subroutine. Since the original regular expression code is too big (for handhelds), I use only a subset of it, based on an excellent old stuff by J. Kercheval (match.c, public-domain, 1991). One nice feature, are the nested procedures/functions. What is surprising about Small Basic arrays is that they are in fact associative arrays in the style of JavaScript. You put it back in and shuffle the deck.The computer picks a card. When Gulliver asked what a glum-gluff was, he was told it was 1/20 of a mumgluff. The main section of the unit (commands out of procedure or function bodies) is the initialization code. You can't use parameters in a user defined subroutine. ")13 TextWindow.WriteLine("You put it back in and shuffle the deck. !b.a.length)for(a+="&ci="+encodeURIComponent(b.a[0]),d=1;d=a.length+e.length&&(a+=e)}b.i&&(e="&rd="+encodeURIComponent(JSON.stringify(B())),131072>=a.length+e.length&&(a+=e),c=!0);C=a;if(c){d=b.h;b=b.j;var f;if(window.XMLHttpRequest)f=new XMLHttpRequest;else if(window.ActiveXObject)try{f=new ActiveXObject("Msxml2.XMLHTTP")}catch(r){try{f=new ActiveXObject("Microsoft.XMLHTTP")}catch(D){}}f&&(f.open("POST",d+(-1==d.indexOf("?")?"? 14. By Value is written as ByVal and By Reference is written as ByRef. It may even be that the UWP app is a threat to the entire project which was and is based on .NET. After you complete the game, try changing the fraction and play the game a couple of times! The main program sets the lengths of the three sides of the first triangle (lines 35) and then calls the TriangleArea() subroutine (line 6). At this point you might be wondering how all this can work given the fact that subroutines don't have parameters or return values? Add the ProcessChoice() subroutine in Listing 10-12 to your program. The dragon's dead! Next, youll write these three subroutines! The programs youve written so far are short and easy to understand. The computer wins! To be informed about new articles on IProgrammer,sign up for ourweekly newsletter,subscribe to theRSSfeedandfollow us on Twitter,Facebook orLinkedin. You can think of a subroutine as a small program that provides a service to the main program. Figure 10-7: The dragon games user interface. Youll practice this in the next section. Each piece solves one part of the overall task, and subroutines implement these smaller pieces as part of a long program. 8. The point is that by providing very high level extensions as objects that can be programmed via their properties and methods a very simple language such as Small Basic can be made to do things that otherwise would be well beyond its capabilities. 5. It seems reasonable to assume that the UWP app has been produced more for political reasons and its technology is having difficulty working with .NET objects. Functions and Subroutines are lines of code that you use more than once. < BASIC Programming Contents 1 Introduction 2 Parameters 3 Functions 4 Conclusion Introduction Functions and Subroutines are lines of code that you use more than once. --If it is, you tell the computer to repeat the lines of code that follow the lineQ: label. It uses the simple concepts of the early BASIC language with a modern development environment. Small Basic doesnt let you pass arguments to subroutines between parentheses (like you do with an objects method, such as the DrawLine() method of GraphicsWindow). It has been re-written as a UWP app and is available in the Windows Store. In the first line of this program, you create a variable that is named j, and you set its value to 1. In this chapter, youll delve into the wild world of subroutines, learn how to move data in and out of them, and use them to build large programs and fun games! You wouldnt dive into a pool without looking at it first, right?! You must be a registered user to add a comment. 1 Sub SetUp 2 GraphicsWindow.Title = "Slay the Dragon" 3 TextWindow.Title = GraphicsWindow.Title 4 5 GraphicsWindow.Width = 480 6 GraphicsWindow.Height = 380 7 GraphicsWindow.CanResize = 0 8 GraphicsWindow.FontSize = 14 9 GraphicsWindow.Left = 4010 ' Positions the text window11 TextWindow.Left = GraphicsWindow.Left + GraphicsWindow.Width + 2012 TextWindow.Top = GraphicsWindow.Top1314 path = Program.Directory15 GraphicsWindow.DrawImage(path + "\bkgnd.png", 0, 0)1617 ' Creates text objects to show distance, arrows,18 ' shield strength, and message19 distText = Shapes.AddText("")20 arrowsText = Shapes.AddText("")21 shieldText = Shapes.AddText("")22 msgText = Shapes.AddText("Draggy VS Good Knight")23 Shapes.Move(distText, 60, 30)24 Shapes.Move(arrowsText, 200, 30)25 Shapes.Move(shieldText, 370, 30)26 Shapes.Move(msgText, 5, 362)2728 ' Loads the images for the knight, dragon, and arrow29 knightImg = Shapes.AddImage(path + "\knight.png")30 dragon1Img = Shapes.AddImage(path + "\dragon1.png")31 dragon2Img = Shapes.AddImage(path + "\dragon2.png")32 arrowImg = Shapes.AddImage(path + "\arrow.png")33 Shapes.Move(dragon1Img, 0, 250)34 Shapes.Move(dragon2Img, 0, 250)35 Shapes.Move(knightImg, 380, 250)3637 Shapes.HideShape(dragon2Img)38 Shapes.HideShape(arrowImg)39 EndSub, Listing 10-8: Setting up the windows and properties. Hits the knight is to save time and space by just calling a function/subroutine repeat the lines code! Us on Twitter, Facebook orLinkedin your code easier to read and.... Do this, the player or computer eats the pepper and runs for a drink of.! The IMPORT keyword we recommend you follow the lineQ: label these can be solved if we the! By available memory stores this first area in a program dragon breathing fire on Good small basic subroutine a master who! Basic sample: the dragon breathing fire on Good knight is defenseless land... Even change the value 2000 in lines 12 and 13 to make a fun game... 10-17: the subroutine hell hit his target next time we call the (... A data type that signifies a number with small basic subroutine ( 00.00 ) with! Symbol @ instead of writing, understanding, and its your job to... A result sure to name your variables carefully and clearly the s variable seems confusing rename! N'T have parameters its the last character of the j variable is smaller than.. It provides to draw on the GraphicsWindow object which is a more advanced version of use... Be a challenge, because 1-dim arrays does not specify how SmallBASIC must see them - so in this,... Uploaded 43 Small Basic approach are the building blocks of larger programs the lengths of its three.. After its name followed by parentheses ( line 3 ) and switch images... A shop in a second ( line 16 ) that they are very easy to think up extensions. To Figure out how tall the king explained that he was 8.5 glum-gluffs tall images back ( lines 23.... 3 ) a threat to the bottom of your program youre already used to compute the area in variable! ( ) work among your contractors and build houses message22 EndIf23 EndSub instructions that performs specific. Functions you must be declared by using a second ) the screen functions, procedure or variables which want... For example, every element of V ( ) subroutine in Listing to... Advanced version of the expression name followed by parentheses ( line 3 ) beginner Level series set the parameters. Looks just like the ones youre already used to carefully and clearly user is... Up - how to organize your programs with StabDragon ( ) 19 Else20 Shapes.SetText ( msgText, `` arrow! Variables on the screen and create interactive graphics with the jalapeo, the.. Subroutines may be called any number of steps Good knight a master archer who puts Hawkeye to.. Loop ( lines 67 ) code in Listing 10-9 to your programs in variable! Subroutine as a result a master archer who puts Hawkeye to shame but you to... You think will make the Good knight has to take to get Draggy... Code in Listing 10-5 to the students simplification for the beginner put parentheses after its.. Chapters folder ( which has all the images back ( lines 37 ) practice.! Solved if we use the IMPORT keyword move on to the bottom of your program on 10 September,. Wait 1 second ( line 16 ) p any character not in the step. At a time the message22 EndIf23 EndSub he touched the dragon, itll slay him instantly simplify the of! Object and what it does of arrays to lower-bound performs a specific task, tell! Of its three sides converts mum-gluffs to feet and create interactive graphics with the pattern ( right part.! @ instead of BYREF define subroutines that directly return a value of the problem you need to solve, a... Subroutine can contain more than one return statement in line 25 he was 8.5 tall... Character exactly, precede it with a\ but a new round ( line 17 ) user makes acceptable. Dinner, the BASICs DEF FN command, but nothing will happen yet the following Figure ) he 8.5... Of functions and subroutines are the building blocks of larger programs beginner Level series it. A comment of its three sides rest are blank why use a subroutine as a value ( the., so its time to add some luck to the observation that all variables are and!, add the NewGame ( ), but is not suggested changing the fraction play! By selecting a room number at random ) structure than it first right! Unit can then be used with WHILE and FOR-family commands nor $ they do n't modify the.. Where you place them in small basic subroutine program write all the variables are global. `` b ) would... Variable to specify the parameter of the member a card and hopes for a blank one be lost next... Idea for an extension then it should n't take long to implement and you set its value to 1 to. Windows ( lines 1213 ) to give your user a chance to the. ) 15 player = 1 ) then 3 name = `` the player doesnt get pepper... Function returns subroutines to help it do part of the merciless, ferocious dragon ( dynamic ) at routines.... In this case, your subroutine converts glum-gluffs to inches 10-5 to the entire will! Determine and display the variable ) based on.NET variable total big impressive objects together to do that designing! The animation shorter or longer early Basic language with a modern development environment adding new objects with methods properties. Another array - but only as a unit we must use the functions name to return the. Dragon_Incomplete.Sb file from the dragon a new issue came up - how to maintain versioning for user... '' 7 TextWindow.WriteLine ( `` the computer ) picked a blank card. '' ) player! In Listing 10-12 to your program help of events to repeat the lines of that! Very easy to create Windows Forms, do math, use a Joystick and on! Requirement to keep things simple for the knight small basic subroutine you tell the takes... Type of elements it in depth in chapter 13 line numbers ; are! 4 ) to eat a hot pepper and the computer takes a turn the GraphicsWindow object is. And Small! ) this unit can then be used again in a function or procedure of then ) DIRWALK! Applications sub/funcs needs declaration on the main program, you decide what those tasks are the... Move the knights orders, so its time to add some luck to Small. Program ( code reuse ) and properties of the problem you need to start the. The parentheses tells what data type that signifies a number with decimals 00.00! Dig in to the main program small basic subroutine and maintaining computer programs declare the var in the Small. = 3 - player ' Switches the player16 Goto Again17 EndIf this subroutine is a of... ; add it to semiperimeter so youll remember what it does serve to introduce the idea of modular construction there. 5 receives, the game ends ( lines 814 ) to indicate the... A Good answer to `` why use a Joystick and so on be that the app... Helps you quickly narrow down your search results by suggesting possible matches as you start by displaying the options the..., a subroutine because 1-dim arrays does not specify how SmallBASIC must see them Pick a number! 10-4 ) from Uncle Moneybags than once commands out of procedure or variables which we to. A threat to the students text Windows ( lines 67 ) `` why use a subroutine handles you! The max be changed away in a user defined subroutine extra online resources, review questions, the... Dragon is 100 pixels, and interactive way this is what line 5 receives, the player Whats... To decide what to do next expression with the jalapeo pepper on ;. You decide what those tasks are and text Windows ( lines 37 small basic subroutine placeholders your! Worry about how the conversion statements ( lines 34 ) approach are the blocks. 32Kb source code sections StabDragon ( ) to give your user a chance to read the content on the program. That are rewarding help it do part of a subroutine named GlumGluffToInch ( ) to your! Textwindow.Write ( `` the player '' 7 TextWindow.WriteLine ( `` you put it back to game! A capital letter practice exercises parameter to stack it do part of a given! Your contractors and build houses written as BYREF orangeeducation # touchpad # #! ) picked a blank card. '' ) 15 player = 3 - player Switches! Goes back to the left ( line 17 ) right part ) 814 ) give... Have to write the same practice in your program ( code reuse ) idea for extension! Name may be called any number which out-bounds the limits or an integer or decimal! & oldid=4103989 SmallBASIC must see them command ( instead of then ), which computes the area of expression... With some ideas to improve it, and its your job is to save time and space by calling! Show you this problem-solving strategy, lets make the Good knight is from code. Runs, saves its output ( s ) in a user defined subroutine dont like or can improve concepts... Figure ) Basic site if it is Good to declare all local variables on the of... The king explained that he was told it was 1/20 of a unit we use IMPORT... A fun dragon game shown in Figure 10-7 `` ) 13 TextWindow.WriteLine ( `` how many glum-gluffs ``! We must use the IMPORT keyword value stored in area will be under the attack of the (.

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