Different methods to reverse a string in C/C++
Given a string, write a C/C++ program to reverse it.
- Write own reverse function by swapping characters: One simple solution is to write our own reverse function to reverse a string in C++.
CPP
// A Simple C++ program to reverse a string#include <bits/stdc++.h>using namespace std;// Function to reverse a stringvoid reverseStr(string& str){ int n = str.length(); // Swap character starting from two // corners for (int i = 0; i < n / 2; i++) swap(str[i], str[n - i - 1]);}// Driver programint main(){ string str = "geeksforgeeks"; reverseStr(str); cout << str; return 0;} |
- Output :
skeegrofskeeg
- Using inbuilt “reverse” function: There is a direct function in “algorithm” header file for doing reverse that saves our time when programming.
// Reverses elements in [begin, end] void reverse (BidirectionalIterator begin, BidirectionalIterator end);
CPP
// A quickly written program for reversing a string// using reverse()#include <bits/stdc++.h>using namespace std;int main(){ string str = "geeksforgeeks"; // Reverse str[begin..end] reverse(str.begin(), str.end()); cout << str; return 0;} |
- Output :
skeegrofskeeg
- Only printing reverse:
CPP
// C++ program to print reverse of a string#include <bits/stdc++.h>using namespace std;// Function to reverse a stringvoid reverse(string str){ for (int i=str.length()-1; i>=0; i--) cout << str[i];}// Driver codeint main(void){ string s = "GeeksforGeeks"; reverse(s); return (0);} |
- Output:
skeegrofskeeG
- Getting reverse of a const string:
CPP
// C++ program to get reverse of a const string#include <bits/stdc++.h>using namespace std;// Function to reverse string and return// reverse string pointer of thatchar* reverseConstString(char const* str){ // find length of string int n = strlen(str); // create a dynamic pointer char array char *rev = new char[n+1]; // copy of string to ptr array strcpy(rev, str); // Swap character starting from two // corners for (int i=0, j=n-1; i<j; i++,j--) swap(rev[i], rev[j]); // return pointer of the reversed string return rev;}// Driver codeint main(void){ const char *s = "GeeksforGeeks"; printf("%s", reverseConstString(s)); return (0);} |
- Output:
skeeGrofskeeG
- Reverse string using the constructor : Passing reverse iterators to the constructor returns us a reversed string.
CPP
// A simple C++ program to reverse string using constructor#include <bits/stdc++.h>using namespace std;int main(){ string str = "GeeksforGeeks"; //Use of reverse iterators string rev = string(str.rbegin(),str.rend()); cout<<rev<<endl; return 0;} |
- Output:
skeeGrofskeeG
5. Using a temporary string
C++
// A simple C++ program to reverse string using constructor#include <bits/stdc++.h>using namespace std;int main(){ string str = "GeeksforGeeks"; int n=str.length(); //Temporary string to store the reverse string rev; for(int i=n-1;i>=0;i--) rev.push_back(str[i]); cout<<rev<<endl; return 0;} |
Output:
skeeGrofskeeG
?list=PLqM7alHXFySGg6GSRmE2INI4k8fPH5qVB
This article is contributed by Priyam kakati, Ranju Kumari, Somesh Awasthi and improved by Supratik Mitra, Lakshay Bansal. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
Attention reader! All those who say programming isn’t for kids, just haven’t met the right mentors yet. Join the Demo Class for First Step to Coding Course, specifically designed for students of class 8 to 12.
The students will get to learn more about the world of programming in these free classes which will definitely help them in making a wise career choice in the future.
