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Converting a DWORD into a CHAR array

Posted on 2004-05-02
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Last Modified: 2007-12-19
Ok, I'm going to try to be as clear as possible:

I've got a DWORD, with a value in, which I'm going to assume is 0x441C0010 for this example (it can be anything though). I need to convert it so that it becomes a series of 4 bytes in a char array,so that the first 2 bytes, are the first character's ascii code, the 2nd two are the second character's ascii code etc.

E.g.:

0x441C0010 would become:
myChar[0] = 0x44
myChar[1] = 0x1C
myChar[2] = 0x00
myChar[3] = 0x10

another example:

0x12345678 would become:
myChar[0] = 0x12
myChar[1] = 0x34
myChar[2] = 0x56
myChar[3] = 0x78

Note, those are single characters, and I'd like it done in fairly basic C++ (if possible!).

Many many thanks if you can help!

eAi
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Question by:eAi2k
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4 Comments
 
LVL 48

Accepted Solution

by:
AlexFM earned 375 total points
ID: 10971362
DWORD dw;
char myChar [4];

DWORDToChar(&dw, myChar);

void DWORDToChar(DWORD* pDWORD, char* pChar)
{
    char* p = (char*) pDWORD;

    for ( int i = 0; i < 4; i++ )
        *pChar++ = *p++;
}
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Author Comment

by:eAi2k
ID: 10972364
I managed to fix this problem myself very simply, by just doing:

char myVariable[3]
myVariable[3] = myDword;
myVariable[2] = (myDword >> 8);
myVariable[1] = (myDword >> 16);
myVariable[0] = (myDword >> 24);

eAi
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LVL 39

Expert Comment

by:itsmeandnobodyelse
ID: 10972668
>> char myVariable[3]

You need at least an array of 4 char.

So, change it to

   char myVariable[4]

Regards, Alex


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LVL 39

Assisted Solution

by:itsmeandnobodyelse
itsmeandnobodyelse earned 375 total points
ID: 10972731
You may also do this:

     DWORD  dw      = 0x12345678;
     unsigned char* pc = (unsigned char*)&dw;
     unsigned char  c[4];
     c[3] = pc[0];
     c[2] = pc[1];
     c[1] = pc[2];
     c[0] = pc[3];

Your request is equivalent to turn the byte order of the storage from little-endian to big-endian.

So you may use sockets helper function htonl that made the same

     DWORD  dw      = 0x12345678;
     dw = htonl(dw);
     unsigned char* pc = (unsigned char*)&dw;

Regards, Alex


   

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