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# How can I change a char to a binary!

Posted on 2003-11-23
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With C langluage, I have a char, I want change it to a binary?
for example, char'0', change to binary is 11000.
how can I do it?
0
Question by:lakeryu

LVL 44

Expert Comment

ID: 9806055
On other systems you would use the itoa() function, which allows you to convert an integer to an ASCII string by specifying thebase or radix (in your case, this would be 2 for binary). This is usually used to convert an integer to a base 10 (decimal) string, but can use anything from 2 to 36.

This page contains several methods to create your own atoi() function. If you search for a2i on this page, you will find the one that I would use:
http://dbforums.com/archives/t57204.html

Once you have this itoa() function, you would then call it like this:

char c = '0';
char outString[1024];

itoa((int) c, outString, 2);

To convert the character '0' to it's binary representation.
0

LVL 45

Expert Comment

ID: 9808360
use strtol

long int strtol(const char *nptr, char **endptr, int base);

result = strtol ( start, NULL, 2 );

man strtol ...
0

LVL 5

Accepted Solution

g0rath earned 50 total points
ID: 9850056
#include <stdio.h>

char *int2bin( int aint, int width )
{
char *buf;
int j;
int i = width;

// room for a null
buf = (char *)calloc(1, width+1);
memset(buf,'0',width);

while ( 1 )
{
j = aint % 2;
aint /= 2;

buf[i--] = j == 0 ? '0' : '1';

if (aint == 0 || i == 0)
break;
}
return buf;
}

int main( int argc, char **argv )
{
char achar;

achar = 'z';

printf("%s\n",int2bin(achar,16));
return 0;
}

// this returns 00000000001111010
// mainly this is just to show that all you do is divide by 2 until you reach zero, and reverse the order that you
// recieved the remainders in

// just as easily you could change the base number to 8, for octal, but for 16, you would need some lookup table
// for the A,B,C,D,E,F values

0

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