How to Reverse a String in C++: 4 Simple Methods Explained

Reversing a string is a classic beginner exercise — and a real interview favorite — because it touches indexing, loops, and the standard library all at once. Here are four ways to do it, from the one-liner you’ll use in practice to the manual methods that teach you how it actually works.

Method 1: std::reverse (the practical one-liner)

The <algorithm> header gives you std::reverse, which reverses any sequence in place:

#include <iostream>
#include <string>
#include <algorithm>

int main() {
    std::string word = "hello";
    std::reverse(word.begin(), word.end());
    std::cout << word << '\n';  // olleh
    return 0;
}

This is the method to reach for in real code: it’s tested, optimized, and instantly readable to other C++ programmers. begin() and end() are iterators marking the start and end of the string — if those are new to you, see our iterators guide.

Method 2: build a new string with a backward loop

If you want to keep the original string, loop from the last character to the first and append each one to a new string:

#include <iostream>
#include <string>

int main() {
    std::string original = "hello";
    std::string reversed;

    for (int i = original.length() - 1; i >= 0; i--) {
        reversed += original[i];
    }

    std::cout << original << " -> " << reversed << '\n';  // hello -> olleh
    return 0;
}

Note the loop variable is int, not size_t — length() returns an unsigned type, and an unsigned i would wrap around to a huge number instead of going below 0, causing an infinite loop. That subtle bug catches a lot of beginners. More loop patterns in our loops tutorial.

Method 3: two pointers (the interview classic)

This is what std::reverse does under the hood: two indices, one at each end, swapping as they move toward the middle.

#include <iostream>
#include <string>
#include <utility>  // std::swap

int main() {
    std::string word = "hello";

    int left = 0;
    int right = word.length() - 1;

    while (left < right) {
        std::swap(word[left], word[right]);
        left++;
        right--;
    }

    std::cout << word << '\n';  // olleh
    return 0;
}

This is efficient because it does the reversal in place with no extra memory — just n/2 swaps. Interviewers love this version because it shows you understand indexing rather than just knowing the library call. The same two-pointer pattern powers our palindrome checker.

Method 4: recursion (the learning exercise)

You can also define reversal recursively: the reverse of a string is its last character plus the reverse of everything before it.

#include <iostream>
#include <string>

std::string reverseString(const std::string& s) {
    if (s.empty()) {
        return "";  // base case
    }
    return s.back() + reverseString(s.substr(0, s.length() - 1));
}

int main() {
    std::cout << reverseString("hello") << '\n';  // olleh
    return 0;
}

This version is slower (each call copies a substring), so don’t use it in production — but it’s a great exercise for understanding base cases and the call stack. Our recursion tutorial breaks down how calls like this unwind.

Bonus: copy in reverse with reverse iterators

To get a reversed copy in one line without touching the original:

std::string reversed(original.rbegin(), original.rend());

rbegin() and rend() are reverse iterators — they walk the string backward, and the string constructor copies characters in that order.

Which method should you use?

Use std::reverse in real code, the two-pointer version in interviews when asked to do it manually, and the recursive version to sharpen your understanding. They all produce the same result — the difference is what each one teaches you.

Related Articles

• C++ String Handling: std::string, string_view, and Performance Tips
• C++ Palindrome Program: Strings and Numbers
• C++ Loops Tutorial: for, while, and do-while Explained
• C++ Recursion Tutorial: How Recursive Functions Work
• C++ Iterators Explained: How to Traverse STL Containers for Beginners

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