Small to caps and vice versa

#include <stdio.h>
#include<iostream>
#include <string.h>
using namespace std;

int main() {
   char s[100];
   int i;
   cin>>s;
   for (i = 0; s[i]!='\0'; i++)
   {
      if(s[i] >= 'a' && s[i] <= 'z')
      {
         s[i] = s[i] - 32;
      }
      else if(s[i] >= 'A' && s[i] <= 'Z')
      {
         s[i] = s[i] + 32;
      }
    }
    cout<<s;
    return 0;
 }