Replace Bit Field in a 32-bit Register

Code

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

uint32_t replace_field(uint32_t reg, uint32_t val, uint8_t pos, uint8_t len) {
    // Your code here
    int end=pos+len-1;
    for(int i=pos;i<=end;i++){
        reg&=~(1<<i);
    }

    reg|=(val<<pos);
    return reg;
}

int main() {
    uint32_t reg, val;
    uint8_t pos, len;
    scanf("%u %u %hhu %hhu", &reg, &val, &pos, &len);
    printf("%u", replace_field(reg, val, pos, len));
    return 0;
}

Solving Approach

First make the end bit 
end=pos+len-1
make sure to erase form pos to end (inclusive)
then shift the given bit by pos