18. Set Multiple Bits in 8-bit Register

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

uint8_t set_range(uint8_t reg, uint8_t start, uint8_t end) {
    for (int i = start; i < end + 1; i++) {
        reg |= (1 << i);
    }
    return reg;
    
    // uint8_t mask = ((1 << (end - start + 1)) - 1) << start;
    // (end - start +1) => (3 - 1 + 1) = 3
    // (1 << 3) = 0b1000
    // 0b1000 - 1 = 0b0111
    // 0b0111 << start => 0b0111 << 1 = 0b1110
    // return reg | mask;
}

int main() {
    uint8_t reg, start, end;
    scanf("%hhu %hhu %hhu", &reg, &start, &end);
    printf("%u", set_range(reg, start, end));
    return 0;
}