The program to reverse a given string takes the input string and output reverse of the string. Each of the characters from the input string is extracted one at a time to achieve this task.

Problem Definition

The program takes an input string at run-time using the built-in function fgets (str) where str is a character array. In this array of characters, the beginning characters are exchanged with the ending characters of the string with the help of a temp variable.

For example

If the string is “ELEPHANT”. The letter is ‘E’ and ‘T’ are exchanged until all characters are reversed. The final output is TNAHPELE.

Program Codes – Reverse a String

#include <stdio.h>
#include <string.h>

int main()
{
    char str[100], temp;
    int i, j;

    printf("Enter the string: ");
    fgets(str, sizeof(str), stdin);

    /* Remove newline character if present */
    str[strcspn(str, "\n")] = '\0';

    i = 0;
    j = strlen(str) - 1;

    while (i < j)
    {
        temp = str[i];
        str[i] = str[j];
        str[j] = temp;
        i++;
        j--;
    }

    printf("Reverse string is: %s\n", str);
    return 0;
}

#include <iostream>
#include <string>
using namespace std;

int main()
{
    string str;
    cout << "Enter the string: ";
    getline(cin, str);

    int i = 0, j = str.length() - 1;
    while (i < j)
    {
        swap(str[i], str[j]);
        i++;
        j--;
    }

    cout << "Reverse string is: " << str << endl;
    return 0;
}
import java.util.Scanner;

public class ReverseString {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter the string: ");
        String str = sc.nextLine();

        char[] ch = str.toCharArray();
        int i = 0, j = ch.length - 1;

        while (i < j) {
            char temp = ch[i];
            ch[i] = ch[j];
            ch[j] = temp;
            i++;
            j--;
        }

        System.out.println("Reverse string is: " + new String(ch));
        sc.close();
    }
}
s = input("Enter the string: ")
rev = s[::-1]
print("Reverse string is:", rev)

Output

The output of the above program is given below. When the program ask for a string input, the user enters – MATHEMATICS. The program reverses the string and give following output.

Enter the String: MATHEMATICS
Reverse String is SCITAMEHTAM