print in binary format 2

[italy]

how can I print an integer in binary format like is there any switch with printf or it has to be diffrent way .thanks

 

[jbpelletier]

//this should work
//call:

printf("bin value:%s",iToBin(MyValue));

//using this:
//------convert an unsigned int to bin----------
char * iToBin(int val)
{
char *s_result= (char *)(malloc (16 * sizeof(char)));
char *s_buf = (char *)(malloc (16 * sizeof(char)));

strcpy(s_buf,""
do
{
strcpy(s_result,((val%2)?"1":"0&quot);
strcat(s_result,s_buf);
strcpy(s_buf,s_result);
}while((val/=2)>=1);

return s_result;
}
jb

 

[Salem]

Lots of lovely memory leaks.

 

[jbpelletier]

true.. sry
this should be better

instead of :
char *s_result= (char *)(malloc (16 * sizeof(char)));
use
char *s_result;

before :
return s_result;
add:
free(s_buf);
jb

 

[Salem]

Getting worse I'm afraid, now you're writing to an uninitialised pointer, with
strcpy(s_result,((val%2)?"1":"0&quot);

 

[jbpelletier]

ok well sorry, im confused.. could u tell me how u would do it (well what to change in the code i pasted).. guess i need it:
jb

 

[danielhozac]

Here is how I would do it:

char *iToBin(int value)
{
    char *string = calloc(sizeof(int) * 8 + 1, sizeof(char));
    int i;
    for (i = 0; i < sizeof(int) * 8; i++)
        string[i] = (value & (1 << i)) ? '1' : '0';
    string[i] = '\0';
    return string;
}

//Daniel

 

[Salem]

Well I would do this, to store the result in a buffer

#include <stdio.h>
#include <limits.h>

/*
 * Note use of static store - the result must be used before calling
 * this function again.
 * This for example is wrong
 * printf( &quot;Result=%s %s\n&quot;, iToBin(0x0), iToBin(0xff) );
 */
char *iToBin( unsigned int val )
{
    static char result[CHAR_BIT*sizeof(unsigned int)+1];
    unsigned int mask = 1u << (CHAR_BIT*sizeof(unsigned int)-1);
    char *p = result;

    do
    {
        *p++ = val & mask ? '1' : '0';
    } while ( mask >>= 1 );    
    *p = '\0';
    return result;
}


int main ( ) {
    printf( &quot;Result=%s\n&quot;, iToBin(0x0u) );
    printf( &quot;Result=%s\n&quot;, iToBin(0x55u) );
    printf( &quot;Result=%s\n&quot;, iToBin(0xAAu) );
    printf( &quot;Result=%s\n&quot;, iToBin(0x12345678u) );
    printf( &quot;Result=%s\n&quot;, iToBin(0x87654321u) );
    return 0;
}

 

[jbpelletier]

tanx, i understand what i wasn't!, well a big part of
jb