1. Set or Clear a Specific Bit in a Register

Keeping code simple.

#include <stdio.h>
unsigned char modifyBit(unsigned char reg, int pos, int mode) {
   if (mode == 1) {
       reg |= (1 << pos);  // Set bit
   } else {
       reg &= ~(1 << pos); // Clear bit
   }
   return reg;
}
int main() {
   unsigned char reg;
   int pos, mode;
   scanf("%hhu %d %d", &reg, &pos, &mode);
   printf("%d", modifyBit(reg, pos, mode));
   return 0;
}