puppybasic intro ch. 16 - arrays

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arrays                                                                   
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                  an intro to puppybasic                                 
                                                                         
                  chapter 16: arrays                                     
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
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arrays                                                                   
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arrays make variables more useful and offer a powerful way to handle     
data. for instance: instead of the following code:                       
                                                                         
READ a                                                                   
READ b                                                                   
READ c                                                                   
READ d                                                                   
READ e: PRINT a;b;c;d;e;                                                 
                                                                         
DATA 52,21,19,45,73                                                      
                                                                         
                                                                         
                                                                         
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you could replace it with this:                                          
FOR q=1 TO 5                                                             
READ ab(q)                                                               
NEXT q                                                                   
                                                                         
FOR q=1 TO 5                                                             
? ab(q);                                                                 
NEXT q                                                                   
                                                                         
...which seems unspectacular until you have a bit more than five         
variables to name.                                                       
                                                                         
                                                                         
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another advantage of arrays is that you don't need to know exactly how   
many items you will be storing. for instance:                            
                                                                         
DIM q$(1 to 100)                                                         
                                                                         
OPEN "file" FOR INPUT AS #1                                              
DO: c=c+1                                                                
LINE INPUT #1, q$(c)                                                     
LOOP UNTIL EOF(1) or c => 99                                             
                                                                         
q$(c+1) = CHR$(26): c=0: close                                           
                                                                         
                                                                         
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arrays                                                                   
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will open "file" and store each line in q$(c), c standing for which line 
is stored there. this example limits the possible number of lines to 99, 
and sets the last line to ascii 26 to mark it as the last.               
                                                                         
note the use of DIM(1 to 100) which is required for arrays more than 10  
units in size. it is also necessary to use dim for multidimensional      
arrays:                                                                  
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
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DIM twod(1 to 5, 1 to 5) AS INTEGER 'integers let you use wider arrays   
                                                                         
will allocate an array of 5 units, and each unit will also have 5        
subunits:                                                                
                                                                         
twod(1,1) twod(2,1) twod(3,1) twod(4,1) twod(5,1)                        
twod(1,2) twod(2,2) twod(3,2) twod(4,2) twod(5,2)                        
twod(1,3) twod(2,3) twod(3,3) twod(4,3) twod(5,3)                        
twod(1,4) twod(2,4) twod(3,4) twod(4,4) twod(5,4)                        
twod(1,5) twod(2,5) twod(3,5) twod(4,5) twod(5,5)                        
                                                                         
                                                                         
                                                                         
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arrays                                                                   
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you may find that although 3-dimensional arrays are possible, but that  
the limitations won't allow a 3d array large enough to be useful all     
that often. (i do know someone who used one for a card game, and you may 
be able to use one for a program to solve rubik's cube... although such  
a program already exists.)                                               
                                                                         
incidently, puppybasic tends to demand that most DIM statements come at  
the beginning of a program, but you can change the limits of some arrays     
using REDIM.                                                             
                                                                         
                         -= end of chapter 16 =-                         
                                                                         
                                                                         
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an intro to puppybasic                                      (chapter 16) 
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