C++ program to check if a sentence is a Palindrome or not

Wikipedia defines Palindrome as, “A palindrome is a word, phrase, number or other sequence of units that can be read the same way in either direction (the adjustment of punctuation and spaces between words is generally permitted).”

There are two different kinds of Palindrome. One is on a character by character basis while the other is on a word by word basis. Examples of these two type of palindromes are “Was it a rat I saw?” and “Fall leaves after leaves fall” respectively.

I have written a program in C++ which can check a word, phrase or sentence if it is a palindrome on a character by character basis. It is capable of handling complex sentences with punctuation marks such as “Dammit, I’m mad!”.

The logic I used in this program is almost self evident but still I have written a short explanation of how it works in the following lines. Continue reading

Very Simple C++ programs – Nested loops Demonstration/Examples

Here are some extremely simple programs in C++ for absolute beginner students. I hope these would help them understand how nested loops work in programming. The required pattern of numbers to be printed on screen by a specific program is given before the source code to serve a problem statement.

Required Pattern

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Revised Version: C++ program to check whether a number is prime or not

About two days ago, I published a post namely C++ program to check whether a number is prime or not. One of my kind readers, Jaume commented on that program and gave me some very useful suggestions and tips on improving it. I am very thankful to him for taking the time to improve my understanding. So, here is a revised version of this program. Changes made in this revision include:

  • Use of a while loop instead of the if statement to validate input numbers and accept only non negative integers.
  • Type of the variable decider has been changed from int to bool and a not operator is used to change its value instead of the increment operator.
  • Variable counter has been started from 3 instead of 2 and is incremented by 2 instead of one during each loop and devision by 2 has been made a special case.
  • and … some minor improvements in the prompts given using cout statements.

Source code of this revised program is given below. Continue reading

C++ program to check whether a number is complete square or not

This program inputs a positive integer from user, checks whether it is a complete square or not and outputs the result to the user.


We use three variables in this program. n is used to store the number under check which is input by the user. i is initialized from 0 and then incremented by one during the execusion of a while loop. m is used to store the square of i during each loop. The loop executes as long as square of i i. e m is less than the number n. After this loop, an if selection statement is used to check whether this square which we have obtained as a result of execution of this loop is equal to the number n or not? if, it is, then we tell the user that the number he entered is a complete square. Otherwise we display a message on the screen stating that this number is not a complete square. Continue reading

C++ program to check whether a number is prime or not

I have used three variables in this program namely number, counter and decider. All of them are of integer type. number is used to store the number entered by the user which is to be checked. counter is initialized at 2 and then it is incremented by 1 in each loop and it is used to test the division of number against all integers between 2 and the number itself but excluding itself also. The so called variable decider is used to make decision during the last steps of the program while it is being told to the user that the number he enetered is a prime number.

The number entered by the user is also tested once to make sure that it is a positive number number. If it is not hten the user is promted to enter the number a second time. Hoewver, if the user again enters a negative number then now he will get a wrong output. So it is important to enter only positive numbers while using this program.

If number entered by user is either 0 or 1 then he simply gets a message that the number entered by him is neither prime nor composite.

However, if the number entered is greater than or equal to 2 then testing will start from the while loop. In each iteration of this loop, remainder will be calculated when number is divided by counter. If this remainder equals zero then user will be told that the number entered is not a prime number, the variable decider will be incrimented by 1 and the loop will exit after the break statement is encountered. But if the remainder number % counter is not equal to zero then the variable counter will be incremented by 1 and the loop will start again. As soon as the the variable counter will become equal to the variable number, the execution of the loop will stop. After the loop, their is an if statement. It tests the variable decider if it is equal to zero or not. If it is, then, user will be told that the entered number is a prime number. Please not that decider will not eual zero (i.e. it will be greater than zero) only if it has been tested and told to the user that number is not prime. In this case, it ofcourse makes sense to skip the statements inside this last if statement. If you still have any confusion about any step of this program or you have some alternative way of doing any of these steps then please feel free to share it with me via comments. I shall be very thankful to you. Continue reading