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 PlayBasic Tutorial: Intro To Functions - (2018-07-06)

By: Kevin Picone Added: July 7th, 2018

Category: All,Video,Beginner,Types,List,Functions,Variables,Getting Started,Tutorials

PlayBasic Tutorial: Intro To Functions - (2018-07-06)

     Hi welcome to our Intro to Functions tutorial. In this tutorial we start out with some revision of Gosub / Return statements, which are used to create a simple sub routine. Sub routines are changes in program flow, allowing the programmer to execute a chunk of code that's external to the section they may be writing, then upon completion the control returns to the caller. This is the same basic model that functions introduction to our programming, except functions are more formalized. Meaning they have some strict rules about syntax and intro a new concepts such as scope changes, which sub routines don't have.

The types of functions shown in video are very simple, initially we start by taking a sub routine that prints rows of text and convert that to function. Through this process we encounter our first problem which is variable scope and look at ways to solve it, such as making our variable global, or better yet passing a variable into the function as a parameter . Later in the video, we create our own custom distance function, as well building a function that does some simple string manipulation

NOTE: This video was recorded alive with only a few changes for length..




Example Code:
PlayBasic Code:
      print ProcessString( "-------Hello World-------")
         print ProcessString( "    1234     " )
         

         Dist# = CustomDistance( 100,100,700,300)
         
         print dist#


         for lp =0 to 10
               Print_Lines_function( lp )         
         next
         print "--------------------------------------------------"
         
         sync
         waitkey
   
         end      
      



function Print_Lines_function( LoopCounter )
         print "--------------------------------------------------"
         print "Loop Counter="+str$(LoopCounter)
endfunction 

         
         
Function CustomDistance( X1#,Y1# , X2#,Y2#)
   
         DX# = abs(X1#-X2#)
         DY# = abs(Y1#-Y2#)
         
         DistResult# = sqrt( DX# * DX# + Dy# * DY#)   
   
EndFunction DistResult#

         
         
Function ProcessString( MyString$)   

         MyString$ = trim$(MyString$,"-")

         MyString$ = Replace$( MyString$," ","~" )

EndFunction MyString$


COMMANDS USED: PRINT | SYNC | WAITKEY | STR$ | ABS | SQRT | TRIM$ | REPLACE$ |
Links:

     Get Source Code Example For This Tutorial





 PlayBasic Tutorial: From Arrays To Types (Intro To Types)

By: Kevin Picone Added: June 27th, 2018

Category: All,Video,Beginner,Types,List,Arrays,Variables,Getting Started,Tutorials

PlayBasic Tutorial: From Arrays To Types (Intro To Types) - (2018-06-12)

    This tutorial picks up where the previous variables to arrays tutorial left off, in that it takes the array code, demos that code then we set about converting the parallel array approach shown in the previous tutorial and we build a structure (TYPE) to hold each characters properties. Once the type has been defined that includes all the required properties, we then define a typed array that will house the collection of characters. Later in the video take a look at using typed lists also. So if your struggling with types this could be a good place to start.



Example #1 - Converting the Parallel Arrays To Typed Array

PlayBasic Code:
   Setfps 20

   Number_Of_Characters = 50

   type tCharacter
         Xpos#
         Ypos#
         Xspeed#
         Yspeed#
         Colour
         Size
   endtype


   dim Characters(Number_Of_Characters) as tCharacter 

   
   for lp = 1 to Number_Of_Characters

         ;  Allocate a newe tCharacter and place it's handle
         ;  into the Character(lp) array / container at this position         
         Characters(lp) = new tCharacter
                  
         Characters(lp).Xpos  = rnd(800)
         Characters(lp).Ypos  = rnd(600)
         Characters(lp).Size  = rndrange(16,50)
         Characters(lp).Xspeed = rndrange(-5, 5)
         Characters(lp).Yspeed = rndrange(-5,5)
         Characters(lp).Colour = rndrgb()
         
   next
   
  
  //-------------------------------------------------------
  //---[ MAIN LOOP ]---------------------------------------
  //-------------------------------------------------------
   
  do 
     
        Cls rgb(0,400,20)
        
        for lp = 1 to Number_Of_Characters
           Radius = Characters(lp).Size
            x#=Characters(lp).Xpos
            y#=Characters(lp).Ypos
   

           circlec X#,Y#,Radius,true,Characters(lp).Colour
                    
           x# = wrapvalue(x# + Characters(lp).Xspeed , -Radius, 800 + Radius)
           y# = wrapvalue(y# + Characters(lp).Yspeed , -Radius, 600 + Radius)
          
           Characters(lp).xpos= x#
           Characters(lp).ypos= y#             
        next
          
        Sync
     loop


COMMANDS USED: SETFPS | DIM | NEW | RND | RNDRANGE | RNDRGB | CLS | RGB | CIRCLEC | WRAPVALUE | SYNC |



Example #2 - Converting Typed Array To Typed List

PlayBasic Code:
   Setfps 20

   Number_Of_Characters = 50

   type tCharacter
         Xpos#
         Ypos#
         Xspeed#
         Yspeed#
         Colour
         Size
   endtype


   dim Characters as tCharacter  list 

   
   for lp = 1 to Number_Of_Characters
      
         Characters = new tCharacter
                  
         Characters.Xpos  = rnd(800)
         Characters.Ypos  = rnd(600)
         Characters.Size  = rndrange(16,50)
         Characters.Xspeed = rndrange(-5, 5)
         Characters.Yspeed = rndrange(-5,5)
         Characters.Colour = rndrgb()
         
   next
   
  
  //-------------------------------------------------------
  //---[ MAIN LOOP ]---------------------------------------
  //-------------------------------------------------------
   
  do 
     
        Cls rgb(0,400,20)
        
        for each Characters()
           
           Radius = Characters.Size
            x#=Characters.Xpos
            y#=Characters.Ypos
   

           circlec X#,Y#,Radius,true,Characters.Colour
                    
           x# = wrapvalue(x# + Characters.Xspeed , -Radius, 800 + Radius)
           y# = wrapvalue(y# + Characters.Yspeed , -Radius, 600 + Radius)
          
           Characters.xpos= x#
           Characters.ypos= y#             
        next
          
        Sync
     loop


 


COMMANDS USED: SETFPS | DIM | LIST | NEW | RND | RNDRANGE | RNDRGB | CLS | RGB | CIRCLEC | WRAPVALUE | SYNC |


Links:

    * PlayBasic Tutorial: From Arrays To Types (Intro To Types) Source Code





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