C reverse bits in unsigned integer

Question

I\'m converting an unsigned integer to binary using bitwise operators, and currently do integer & 1 to check if bit is 1 or 0 and output, then right shift by 1 to divide

Answer 1

I believe the question is asking how to not output in reverse order.

Fun answer (recursion):

#include 

void print_bits_r(unsigned int x){
    if(x==0){
       printf("0");
       return;
    }
    unsigned int n=x>>1;
    if(n!=0){
       print_bits_r(n);
    }
    if(x&1){
        printf("1");
    }else{
        printf("0");
    }
}


void print_bits(unsigned int x){
    printf("%u=",x);
    print_bits_r(x);
    printf("\n");
}

int main(void) {
    print_bits(10u);//1010
    print_bits((1<<5)+(1<<4)+1);//110001
    print_bits(498598u);//1111001101110100110
    return 0;
}

Expected output:

10=1010
49=110001
498598=1111001101110100110

Sequential version (picks off the high-bits first):

#include //Defines CHAR_BIT
//....
void print_bits_r(unsigned int x){
    //unsigned int mask=(UINT_MAX>>1)+1u;//Also works...
    unsigned int mask=1u<<(CHAR_BIT*sizeof(unsigned int)-1u);
    int start=0;
    while(mask!=0){
        if((x&mask)!=0){
            printf("1");
            start=1;
        }else{
            if(start){
                printf("0");
            }
        }
        mask>>=1;
    }
    if(!start){
       printf("0");
    }    
}