C Exercises: Check a number is a Happy or not

Last update on May 27 2022 12:18:15 (UTC/GMT +8 hours)

C Numbers: Exercise-13 with Solution

Write a program in C to check a number is a Happy or not.

Test Data
Input a number: 13

Sample Solution:

C Code:

# include <stdio.h>
# include <math.h>
# include <stdlib.h>
# include <stdbool.h>


int SumOfSquNum(int givno)
{
    int SumOfSqr = 0;
    while (givno)
    {
        SumOfSqr += (givno % 10) * (givno % 10);
        givno /= 10;
    }
    return SumOfSqr;
}
bool checkHappy(int chkhn)
{
    int slno, fstno;
    slno = fstno = chkhn;
    do
    {
        slno = SumOfSquNum(slno);
        fstno = SumOfSquNum(SumOfSquNum(fstno));
    }
    while (slno != fstno);
    return (slno == 1);
}
int main()
{
int hyno;
	printf("\n\n Check whether a number is Happy number or not: \n");
	printf(" ---------------------------------------------------\n");
	printf(" Input a number: ");
	scanf("%d",&hyno);

    if (checkHappy(hyno))
	printf("%d is a Happy number.\n",hyno);
    else
	printf("%d is not a Happy number.\n",hyno);
}

Sample Output:

 Input a number: 13                                                                                           
13 is a Happy number.

Pictorial Presentation:

C programming: Check a number is a Happy or not.

Flowchart:

C Programming Code Editor:

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C Programming: Tips of the Day

Static variable inside of a function in C

The scope of variable is where the variable name can be seen. Here, x is visible only inside function foo().

The lifetime of a variable is the period over which it exists. If x were defined without the keyword static, the lifetime would be from the entry into foo() to the return from foo(); so it would be re-initialized to 5 on every call.

The keyword static acts to extend the lifetime of a variable to the lifetime of the programme; e.g. initialization occurs once and once only and then the variable retains its value - whatever it has come to be - over all future calls to foo().

Ref : https://bit.ly/3fOq7XP