After each swap, increment the left pointer and decrement the right pointer to move towards the center of the string. This will swap all the characters in the first half with their corresponding character in the second half. ... // C++ program to reverse a string using two pointers #include <iostream> using namespace std; string reverseString(string &s) { int left = 0, right = s.length() - 1; // Swap characters from both ends till we reach // the middle of the string while (left < right) { swap(s[left], s[right]); left++; right--; } return s; } int main() { string s = "abdcfe"; cout << reverseString(s); return 0; }