Extract Even Bits Only from 32-bit Register

Code

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

uint32_t extract_even_bits(uint32_t reg) {
    uint8_t i;
    uint32_t mask;
    uint32_t post=0;
    for(i=0;i<32;i=i+2){
        if((reg>>i) & 1){
            mask |= (1<<post);
        }
        post++;
    }

    
    return mask;
}

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

Solving Approach