Array in an array

[mnrvovrfc]

Erase can also be used for dynamic arrays, but it is redundant there as Redim includes Dim & Erase. 

The easy answer for Dynamic array is to just REDIM it again.

The same thing was said in two different ways(*). However, it depends on the application. Q(uick)BASIC had to be more competitive because interpreted BASIC was falling behind C too much, and therefore M$ allowed the concept of dynamic memory. So "$DYNAMIC" and "REDIM" and declaring an array with "DIM" with variable subscript were the only ways to have anything like "calloc()" and "malloc()" in C. I'm not sure if "ERASE" existed in GW-BASIC/BASICA but its meaning was changed where it came to dynamic arrays. There had to be some way to free the dynamic memory if it was no longer to be used, because when the first version of QuickBASIC came out, computers couldn't have much more than 640KB RAM for a reasonable price.

(*) But (a big one) that is true as long as the number of dimensions is the same.

Cannot just "REDIM" an already-existing dynamic array changing it from single- to double-dimension, for example. It is not allowed even if "ERASE" were used before a second or further "REDIM". The programming system firmly sticks to the number of dimensions for an array identifier.

From this program:

Code: (Select All)

redim a(1 to 10, 1 to 10)
a(8, 8) = 8
print a(8, 8)
redim a(1 to 8)
a(8) = 64
print a(8)
end

I get this output from QB64PE compiler:

Code: (Select All)

[~/zapp/qbpe]$ ./qb64pe -x fd21.bas
QB64-PE Compiler V3.6.0

Beginning C++ output from QB64 code...
[....................                              ] 40%
Cannot change the number of elements an array has!
Caused by (or after):REDIM A ( 1 TO 8 )
LINE 4:redim a(1 to 8)