1. Set or Clear a Specific Bit in a Register

#include <stdio.h>
unsigned char checkBit(int n,int i){
    return ((n>>i) & 1) == 1 ; 
}
unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    unsigned char bit = checkBit(reg,pos);
    if( (bit==1 && mode==1) || ( bit==0 && mode==0 ) )
        return reg;
    return mode ? reg += (1<<pos) : reg -= (1<<pos);
}

int main() {
    unsigned char reg;
    int pos, mode;
    scanf("%hhu %d %d", &reg, &pos, &mode);
    printf("%d", modifyBit(reg, pos, mode));
    return 0;
}