C++ Program to Check if a String is Palindrome
Posted by Superadmin on August 10 2022 13:10:12

C++ Program to Check if a String is Palindrome

This is a C++ Program to Find if a String is Palindrome.

Problem Description

The program checks if a string is a palindrome or not. A palindrome is a word or a string that reads the same backward and forward.

Problem Solution

1. The program takes a string and stores it.
2. The string is copied into another string from backwards.
3. If both the strings are equal, then the entered string is a palindrome.
4. Else it is not.
5. The result is printed.
6. Exit.

C++ Program/Source code

Here is the source code of C++ Program to Find if a String is Palindrome. The program output is shown below.

```
#include <iostream>
```
```
#include <string.h>
```
```
using namespace std;
```
```
int main()
```
```
{
```
```
    char str1[20], str2[20];
```
```
    int i, j, len = 0, flag = 0;
```
```
    cout << "Enter the string : ";
```
```
    gets(str1);
```
```
    len = strlen(str1) - 1;
```

    for (i = len, j = 0; i >= 0 ; i--, j++)

```
        str2[j] = str1[i];
```
```
    if (strcmp(str1, str2))
```
```
        flag = 1;
```
```
    if (flag == 1)
```

        cout << str1 << " is not a palindrome";

```
    else
```

        cout << str1 << " is a palindrome";

```
    return 0;
```
```
}
```

Program Explanation

1. The user is asked to enter a string and it is stored in the character variable ‘str1’.
2. The length of str1 is stored in ‘len’ using the string function strlen().
3. Using a for loop, str1 is copied into another variable ‘str2’ from backwards.
4. Both the strings str1 and str2 are compared using string function strcmp().
5. A temporary variable flag is used.
6. If str1 is equal to str2, then the entered string is a palindrome, else not.
7. The result is then printed.

Runtime Test Cases

Case 1 :
Enter the string : nun
nun is a palindrome
 
Case 2 :
Enter the string : fast                                                                                                        
fast is not a palindrome
 
Case 3 :
Enter the string : 121                                                                                                         
121 is a palindrome