Extract Even Bits Only from 32-bit Register

Code

#include <stdio.h>
#include <stdint.h>

uint32_t extract_even_bits(uint32_t reg) {
    int in_pos=0;
    int out_pos=0;
    uint32_t res=0;
    while(reg>0){
        if(in_pos%2==0){
            res|=((reg&1)<<out_pos);
            out_pos++;
        }
        reg=reg>>1;
        in_pos++;
    }
    return res;
}

int main() {
    uint32_t reg;
    scanf("%u", &reg);
    printf("%u", extract_even_bits(reg));
    return 0;
}

Solving Approach