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
    uint32_t mask;
    uint32_t extracted;
    for(int i = 0; i<16; i++){
        extracted = ((reg>>(2*i))&1);
        if (extracted){
            mask <<= 1;
        }
        mask |= extracted;
    }
    return mask;
}

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

Solving Approach