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If you are searching for a program for Palindrome in c , c++ and java you are at the right place. Read the complete article.


What is a palindrome?

Palindrome is a string or number, if we read that string or number from backwards then it is same as if we read it from forward.

Example:

  • madam
  • aabaa
  • yytyy
  • abaaba
  • 121
  • 122221

How to check a string is palindrome?

Now lets check various methods of checking for palindrome.

  • By reversing the string.
  • By comparing the characters.
  • Converting a number to string then either reversing or comparing character index.
  • Reversing that number and comaring.

Palindrome in C

Lets use reversing a string to write palindrome program in c using pre-defined strrev( ) function.

//palindrome program in c
#include<stdio.h>
#include<stdlib.h>
#include <string.h>
int main(int argc, char const *argv[])
{
	char string[100];
	//Input a string
	printf("Palindrome in c\n Enter a string:");
	scanf( "%s",string );
	//Creating another reverse string for comaring
	char temp_string[100];
	int length=strlen(string);
	temp_string[length]='\0';
	//copy input string
	strcpy( temp_string,string );
	//reverse input string
	strrev(string);
	//compare both string
	if( strcmp( string,temp_string )==0 )
	{
		printf("\nString is a palindrome\n" );
	}
	else
	{
		printf("\nString is not a palindrome\n" );
	}
	
	return 0;
}
palindrome in c
palindrome in c

Palindrome in C without using string functions

#include<stdio.h>
#include<stdlib.h>
#include <string.h>
#include<math.h>
int main(int argc, char const *argv[])
{
	char string[100];
	//Input a string
	printf("Palindrome in c\n Enter a string:");
	scanf( "%s",string );
	//Now lets compare character by character.
	int length=strlen(string);
	//find middle element
	int middle_element=floor(length/2);
	int j=length-1;
	//start comparing by index
	for( int i=0 ; i<=middle_element ; i++ )
	{
		if( string[i]!=string[j]  )
		{
			printf("\nString is not a palindrome\n" );
			return 0;
		}
		j--;
	}
	printf("\nString is a palindrome\n" );	
	return 0;
}
palindrome in c
palindrome in c

Palindrome number program in C

#include<stdio.h>
#include<stdlib.h>
#include <string.h>
#include<math.h>
int main(int argc, char const *argv[])
{
	
	int number=0;
	//Input a string
	printf("Palindrome in c\n Enter a number:");
	scanf( "%d",&number );
	int temp=number;
	int reverse_number=0;
	while( temp>0 )
	{
		reverse_number=reverse_number*10;
		reverse_number=reverse_number+( temp%10 );
		temp=temp/10;
	}
	if( reverse_number==number )
	{
		printf("\nNumber is a palindrome\n" );
	}
	else
	{
		printf("\nNumber is not a palindrome\n" );
	}
	return 0;
}
palindrome number in c
Output for palindrome number program in c

Palindrome program in C++

#include<bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[])
{
	string str;
	//input a string
	cout<<"Enter a string"<<endl;
	cin>>str;
	string reverse_string;
	//lets reverse a string
	reverse_string=str;
	reverse(reverse_string.begin(),reverse_string.end());
	if( str==reverse_string )
	{
		cout<<"String is a palindrome"<<endl;
	}
	else
	{
		cout<<"String is not a palindrome"<<endl;
	}
	return 0;
}
palindrome in c++
Output for palindrome in c++

Palindrome in C++ character comparisn method

#include<bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[])
{
	string str;
	//input a string
	cout<<"Palindrome in c++\nEnter a string:"<<endl;
	
	cin>>str;
	//find length of string
	int middle_element=floor(str.size()/2);
	int j=str.size()-1;
	//start comparing by index
	for( int i=0 ; i<=middle_element ; i++ )
	{
		if( str[i]!=str[j]  )
		{
			cout<<"String is not a palindrome"<<endl;
			return 0;
		}
		j--;
	}
	cout<<"String is a palindrome"<<endl;	
	return 0;
}
palindrome in c++
palindrome in c++

Palindrome number program in C++

#include<bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[])
{
	
	int number=0;
	//Input a string
	cout<<"Palindrome number in c++\n Enter a number:"<<endl;
	cin>>number;
	int temp=number;
	int reverse_number=0;
	while( temp>0 )
	{
		reverse_number=reverse_number*10;
		reverse_number=reverse_number+( temp%10 );
		temp=temp/10;
	}
	if( reverse_number==number )
	{
		cout<<"Number is a palindrome"<<endl;
	}
	else
	{
		cout<<"Number is not a palindrome"<<endl;
	}


		
	return 0;
}
palindrome numaber in c++
Output palindrome numaber in c++

Palindrome in java by string reverse method

package palindrome;

import java.util.Scanner;

public class palindrome {

	public static void main(String[] args) {
		//read a string
		Scanner stdin=new Scanner(System.in);
		System.out.println("Enter a string");
		String str=stdin.nextLine();
		String rev_str="";
		//reverse a string
		for( int i=str.length()-1 ; i>=0 ; i-- ) 
		{
		  rev_str=rev_str+str.charAt(i);
		}
		//compare both strings
		if( str.compareTo(rev_str)==0  )
		{
			System.out.println("String is a palindrome.");
		}
		else
		{
			System.out.println("String is not palindrome.");
		}
		
	}

}

palindrome in java
Output palindrome in java

Palindrome in java by Character comparisn method

package palindrome;

import java.util.Scanner;

public class palindrome {

	public static void main(String[] args) {
		//read a string
		Scanner stdin=new Scanner(System.in);
		System.out.println("Enter a string");
		String str=stdin.nextLine();
		int j=str.length()-1;
		//compare index
		boolean flag=true;
		for( int i=0 ; i<Math.floor((j/2)) ; i++ )
		{
			if( str.charAt(i)!=str.charAt(j) )
			{
				flag=false;
				break;
			}
			j--;
		}
		if( flag )
		{
			System.out.println("String is a palindrome.");
		}
		else
		{
			System.out.println("String is not palindrome.");
		}
		

		
	}

}
palindrome in java
Output palindrome in java

Palindrome number in java

package palindrome;

import java.util.Scanner;

public class palindrome {

	public static void main(String[] args) {
		//read a string
		Scanner stdin=new Scanner(System.in);
		System.out.println("Enter a number");
		int number=stdin.nextInt();
		int rev=0;
		int temp=number;
		while(temp>0)
		{
			rev=rev*10;
			rev+=temp%10;
			temp=temp/10;
		}
		if( rev==number )
		{
			System.out.println("Number is a palindrome.");
		}
		else
		{
			System.out.println("Number is not palindrome.");
		}
		
		
	}

}
palindrome number in java
Output palindrome number in java

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