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

To reverse a string in C++, you can use the std::reverse function from the algorithm header, which reverses the string in place. Alternatively, you can create a new reversed string by iterating from the end to the beginning of the original string.

Syntax

The common way to reverse a string in C++ is using the std::reverse function from the algorithm library. It takes two iterators: the start and the end of the string range to reverse.

• std::reverse(str.begin(), str.end()); reverses the entire string str in place.

cpp

std::reverse(str.begin(), str.end());

Example

This example shows how to reverse a string using std::reverse. It prints the original string and the reversed string.

cpp

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

int main() {
    std::string str = "hello world";
    std::cout << "Original string: " << str << std::endl;
    std::reverse(str.begin(), str.end());
    std::cout << "Reversed string: " << str << std::endl;
    return 0;
}

Output

Original string: hello world
Reversed string: dlrow olleh

Common Pitfalls

One common mistake is trying to reverse a string without using iterators or modifying the original string incorrectly. For example, using a loop to swap characters manually but messing up indices can cause errors.

Also, forgetting to include the <algorithm> header will cause a compilation error when using std::reverse.

cpp

#include <iostream>
#include <string>

int main() {
    std::string str = "hello";
    // Wrong: swapping without correct indices
    for (int i = 0; i < str.size() / 2; ++i) {
        char temp = str[i];
        str[i] = str[str.size() - i - 1];
        str[str.size() - i - 1] = temp;
    }
    std::cout << str << std::endl; // This will reverse correctly

    // Right way: use std::reverse
    #include <algorithm>
    std::reverse(str.begin(), str.end());
    std::cout << str << std::endl; // Correct reversed string
    return 0;
}

Output

olleh
hello

Quick Reference

• std::reverse: reverses string in place using iterators.
• Manual loop: swap characters from start and end moving inward.
• Include <algorithm> for std::reverse.
• Strings are mutable in C++ so you can change them directly.

Key Takeaways

Use std::reverse from to reverse strings easily and safely.

Remember to include header to use std::reverse.

Manual reversal requires careful swapping of characters from both ends.

Strings in C++ can be reversed in place because they are mutable.

Avoid off-by-one errors when manually reversing strings.