C++程序交换一对字符

char temp = String_variable[ <first index> ]
String_variable[ <first index> ] = String_variable[ <second index> ]
String_variable[ <second index> ] = temp

#include <iostream>
using namespace std;
string solve( string s, int ind_first, int ind_second){
   if( (ind_first >= 0 && ind_first < s.length()) && (ind_second >= 0 && ind_second < s.length()) ) {
      char temp = s[ ind_first ];
      s[ ind_first ] = s[ ind_second ];
      s[ ind_second ] = temp;
      return s;
   } else {
      return s;
   }
}
int main(){
   string s = "A string to check character swapping";
   cout << "Given String: " << s << endl;
   cout << "Swap the 6th character and the 12th character." << endl;
   s = solve( s, 6, 12 );
   cout << "\nUpdated String: " << s << endl;
   s = "A B C D E F G H";
   cout << "Given String: " << s << endl;
   cout << "Swap the 4th character and the 10th character." << endl;
   s = solve( s, 4, 10 );
   cout << "Updated String: " << s << endl;
}

Given String: A string to check character swapping
Swap the 6th character and the 12th character.
Updated String: A stricg to nheck character swapping
Given String: A B C D E F G H
Swap the 4th character and the 10th character.
Updated String: A B F D E C G H