C printing bits

Question

I am trying to write a program in C that prints bits of int. for some reason i get wrong values,

void printBits(unsigned int num){
    unsigned int size = si         


        

Answer 1

How about this Macro:

#define print_bits(x) \
do { \
        unsigned long long a__ = (x); \
        size_t bits__ = sizeof(x) * 8; \
        printf(#x ": "); \
        while(bits__--) putchar(a__ & (1 << bits__) ? '1' : '0'); \
        putchar('\n'); \
} while(0)

Use like:

char c = 3;
int i = -1;
print_bits(c);
print_bits(i);

output:

c: 00000011
i: 11111111111111111111111111111111

If you don't want to print the expression 'x' which is the argument to 'print_bits' remove the line:

printf(#x ": "); \

This Marco can be used on any primitive datatype and the expression 'x' will be evaluated only once. So you should be safe from side effects.