In schools or computer classes you may have often heard of the term, ‘palindrome’!
But have you ever thought, you would encounter this concept more than often in your coding journey.
In coding interviews, you may often come across the topic of palindrome string.
A palindrome string is represented as the one that reads the same from left to right and right to left.
The best example of it would be ‘madam’ which you can read as the same for both backward and forward.
Though, there are certain approaches involved in checking if the given string is palindrome or not.
To give you an edge and help you gain knowledge momentum, we have explained this concept in-depth.
Let’s get started!
What is palindrome?
Palindrome is defined as the sequence of certain characters which when getting reversed gives the same result as the exact sequence of characters.
As the word ‘rotator’ when spelt in the backward direction will give you the word ‘rotator’
Checking if a given string is palindrome or not
To check if a given string is palindrome or not, we can make use of the input string as the argument to return the function value as true. Otherwise, it will return false if the string is not palindrome.
The steps to take in this case are:
- Take any string as the given input
- Compare both the first and the last character of that string. If they are considered equal, compare the given second or second last character in a given string until you will reach the middle of your string
- If any of its characters won’t match at any given iteration, the string would not be a palindrome
Methods to check if the string is palindrome or not
You can make use of certain methods to check if the given string is palindrome or not
Using reverse and the compare method
To reverse a string, we can make use of the reverse and the compare method.
In this method, we will find a reversed string by comparing it to that of the original string. If the strings match, it would be palindrome.
You can follow these steps:
- First, start by the declaration of ispalindrome() function to pass it in the given string argument
- In the function body, we will get a reversal of the inputs with the slice operator as string [::-1]. The -1 would be the step parameter which ensures that the slicing works with one step back
- If all the reversed string matches your input, it will be palindrome
- Or else, it will not be a palindrome
Using the for loop method
This is another method, which you can use to reverse a given string. In this method, we can use the for loop function in order to iterate all the characters in a string to join each of the characters that gets stored in an empty variable which will get the declaration in it.
For that you can follow these steps:
- Enter your input string
- We will declare the empty string variable revstr which you can store in a reversed string.
- Next, we can make use of the for loop in order to iterate all of the characters in a given string in order to concentrate all the elements that are stored in a revstr variables
- Once the execution of the loop gets completed, you can make use of the if-else loop
- If the reversal string matches in the case of the input string which is palindrome, otherwise it will not be a palindrome.
Using the while loop method
You can also make use of the while loop method which is considered a better option than the for loop method as in this case the strings will not need any reassigning during the execution of a loop.
In this case, any kind of program will not consume more memory for the large strings.
The steps to follow in this case are:
- We can start with the declaration of the ispalindrome() function to pass the string arguments
- We will define the first and the last variable to assign the last variable as -1 in the len string
- Next, we will make use of a while loop where we can iterate through the characters of an input string from its start till the end of a loop, then, the loop would evaluate if the nth index values at the front will match with the nth index values at the back. If it comes out as true, the function may return the value of a string as the palindrome
- If the first and its last character will not match, then the loop may break in that case. Though, there will not be the need to check an entire string.
Using reverse and join method
The in-built reversed() function cycles through all the string characters in a reverse order. We can match the revered string with that of the input string to show if it is palindrome or not.
However, in this method, we will be using the join()method instead of using the slicing operator.
We can declare the ispalindrome()function to pass an argument. In a function body, we can make use of the reversed() function in order to iterate through all characters. All reversed characters would be joined with the join() function to store the revstr variable.
Additional learning - features of asp net
When you are involved in your coding preparation, you can also learn the concept of features of asp net. The asp.net is touted as the open-source framework which is basically known for its versatile features like high-performance, cross-platform support, comprehensive environment for development, particular language independence and much more.
The concept of Palindrome string is an essential coding preparation topic which should be known to all the coding aspirants. Learn the knits and grits about this topic with our blog post and strengthen your knowledge base. \
Happy learning, happy coding!