int foo(char high,char low){
high -= ( high>=0 && high<=9 )?'0':'A';
low -= ( high>=0 && high<=9 )?'0':'A';
return ((int)(high*10+low))>>16;
}

int main(void){
printf("%d",foo('0','1'));
return 0;
}

不知道是不是这个意思