Extract Even Bits Only from 32-bit Register

Code

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

uint32_t extract_even_bits(uint32_t reg) {
    // Your code here
    int i=(sizeof(int)*8)-1;
    int res=0;
    for (i=i-1;i>=0; i-=2)
    {
        res |= (((reg>>i)&1)<<(i/2));
    }
    return res;
}

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

Solving Approach