PDA

View Full Version : [SOLVED] C: string to binary

Psycho.mario
February 28th, 2011, 08:49 PM
Hi, I'm quite new to C so bear with me. I have an address in a string, which takes the form of (for example) "7c802446", Can somebody tell me how I can convert this from the string its in, to a string that is half the length, as the binary equivalent. What I mean is converting 7c802446 to \x7c\x80\x24\x46. I haven't explained this very well, ask extra questions if you need.

Thanks

schauerlich
February 28th, 2011, 09:26 PM
You can use sscanf to read a hex number from a string. It might also be just as simple to do the conversion yourself.

Psycho.mario
February 28th, 2011, 09:47 PM
char test[4]; //output
char *p, *q;
sscanf(p, "%2x", q);
}
*q = '\0';

schauerlich
February 28th, 2011, 09:52 PM
What if you have an odd-length string? You can't be guaranteed that anything but the last byte is 0 for a properly formed C string. The next byte after may be anything.

Psycho.mario
February 28th, 2011, 09:58 PM
True... The actual program is for windows, and it gets its string from getprocaddress. all i need to do is prepend '0' until it gets to a length of 8. I thought it would be okay to post here becuase the actual question wasn't windows related.

foxmuldr
March 1st, 2011, 11:39 AM
Hi, I'm quite new to C so bear with me. I have an address in a string, which takes the form of (for example) "7c802446", Can somebody tell me how I can convert this from the string its in, to a string that is half the length, as the binary equivalent. What I mean is converting 7c802446 to \x7c\x80\x24\x46. I haven't explained this very well, ask extra questions if you need.

Thanks

int result = foo("7c802446");

int foo(char* src)
{
int length = strlen(src);
int value = 0;
for (i = 0; i < length; i++)
{
if (src[i] >= '0' && src[i] <= '9')
value = (value << 4) + (src[i] - '0');
else if (src[i] >= 'a' && src[i] <= 'f')
value = (value << 4) + (src[i] - 'a' + 10);
else if (src[i] >= 'A' && src[i] <= 'F')
value = (value << 4) + (src[i] - 'A' + 10);
else
break; // Some other character, we're done
}
return(value);
}