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 index = 0;
    uint32_t val = 0;
    while (reg)
    {
        val |= ((reg&1U)<<index);
        index++;
        reg = reg>>2;
    }
    return val;
}

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

Solving Approach

I check the value of the first bit and add it to the val variable in its corresponding position index. The I right shift the reg by 2 to get the next even-positioned bit.

When there is no more 'ones' in reg, the while loop exits and returns val.