1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifiedregister (unsigned char reg, int pos, int mode);

int main()
{   
    unsigned char reg ;
    int pos, mode;
    scanf("%hhu %d %d",&reg,&pos,&mode);

    int result = modifiedregister(reg,pos,mode);
    printf("%d", result);
    return 0;
}
unsigned char modifiedregister (unsigned char reg, int pos, int mode){
    if (mode == 1){
        reg |= (1 << pos);
    }
    else{
        reg &= ~(1 << pos);
    }
    
    return reg;
}