Extract Even Bits Only from 32-bit Register

Code

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

uint32_t extract_even_bits(uint32_t reg) {
    
    uint32_t res = 0x0;
    
    if (reg)
    {
        for (uint8_t i = 0; i < 8*sizeof(reg); i++)
        {
            // Save last bit
            if (i % 2 == 0)
                res |= (reg & 1) << (i / 2);
            
            // Pop
            reg >>= 1;
        }

        return res;
    }
    
    return 0;
}

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

Solving Approach