Reverse bit pattern in C

Question

I am converting a number to binary and have to use putchar to output each number.

The problem is that I am getting the order in reverse.

Is the

Answer 1

Let me guess: you have a loop that prints the 0th bit (n&1), then shifts the number right. Instead, write a loop that prints the 31st bit (n&0x80000000) and shifts the number left. Before you do that loop, do another loop that shifts the number left until the 31st bit is 1; unless you do that, you'll get leading zeros.

Reversing is possible, too. Somthing like this:

unsigned int n = 12345; //Source
unsigned int m = 0; //Destination
int i;
for(i=0;i<32;i++)
{
    m |= n&1;
    m <<= 1;
    n >>= 1;
}