Char Array cpp

[ragdog]

Hello Again

I have only a little question about this cpp Array

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static char str[20][100] = {' ',};

Ist this correct in Masm i try to understand a cpp source

str             db 20, 100 dup(0)


Regards,

[dedndave]

i am not sure, but it looks like a 20 x 100 array

[ragdog]

Hello Dave

I also think, and what is {' ',}; first char is a space?

[Vortex]

Hello ragdog,

That code will produce one space character followed by 1999 NULL characters.

Disassembling the code:

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.386
option dotname
.model flat

public _main

_data   SEGMENT DWORD PUBLIC 'DATA'

@8      label byte
        db 20H, 00H, 00H, 00H, 00H, 00H, 00H, 00H
        db 00H, 00H, 00H, 00H, 00H, 00H, 00H, 00H
        .
        .
        .
        db 00H, 00H, 00H, 00H, 00H, 00H, 00H, 00H

_data   ENDS

[dedndave]

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static char str[20][100] = {' ',};

i believe that creates an array of 20 strings, 100 characters each, and fills them with spaces
i am not a C guy, so i may be wrong
each of the 20 strings might be zero-terminated, too - i don't know

[ragdog]

Thank you both

_data   SEGMENT DWORD PUBLIC 'DATA'

@8      label byte
        db 20H, 00H, 00H, 00H, 00H, 00H, 00H, 00H
        db 00H, 00H, 00H, 00H, 00H, 00H, 00H, 00H
        .
        .
        .
        db 00H, 00H, 00H, 00H, 00H, 00H, 00H, 00H

_data   ENDS

Thats right Vortex i understand the same but gives a syntax for it in Masm

expl:

str   2000 dup (?) <{" "}>   ; i know thats not works ;)

Ok a solution is :
str     db 20h
   db 1999 dup (?)

But i have think it gives a similar solution like cpp

[dedndave]

i would probably do this

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    .DATA?

str db 2000 dup(?)

    .CODE

start:
    mov     edi,offset str
    mov     ecx,sizeof str/4
    mov     eax,20202020h
    rep     stosd

[ragdog]

Right Dave this is a simply and knowing solution but i have think it is posible in Masm to define in the data section like cpp

[dedndave]

of course you can

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    .DATA

str db 2000 dup(20h)

that makes the EXE almost 2 KB larger though

[ragdog]

Right

I use now a Allocated memory and add the first char a space

Thanks you,

[hutch--]

Try this algo.

http://masm32.com/board/index.php?topic=4050.0

[mabdelouahab]

Code Select Expand


str db 20*100 dup(" ")


[Vortex]

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str db 20*100 dup(" ")


You probably didn't read Dave's posting. Your executable will be bigger because of that data block.

[rrr314159]

Hello ragdog,

The closest MASM comes to that cpp syntax is this:

str db 20 dup (100 dup (' ',))

This fills all 2000 bytes with 20h. I *think* cpp does the same, the other 1999 are not zero's; but I hate cpp so have a memory block here. The rows are not 0-delimited.

Have a look at this chapter from "The Art of Assembly", Section 5.6.1 Arrays.

Yes, this will increase your .exe by 2K, but that's what cpp does; static arrays are always initialized, with 0's if nothing else.

Well, since you have to deal with it, I hope u like cpp better than I do. Used to love C but after C++ even that's distasteful. Good luck!

[ragdog]

Thank you all for this infos

Yes, this will increase your .exe by 2K

What is 2 k todays gives programs with many Mbs  :lol:

But my goal was to understand this cpp source