C Exercises: Check a number is a Happy or not
C Numbers: Exercise-13 with Solution
Write a program in C to check a number is a Happy or not.
Test DataInput 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:
Flowchart:

C Programming Code Editor:
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Previous: Write a program in C to display the first 10 catlan numbers.
Next: Write a program in C to find the happy numbers between 1 to 1000.
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C Programming: Tips of the Day
Why do C and C++ compilers allow array lengths in function signatures when they're never enforced?
It is a quirk of the syntax for passing arrays to functions.
Actually it is not possible to pass an array in C. If you write syntax that looks like it should pass the array, what actually happens is that a pointer to the first element of the array is passed instead.
Since the pointer does not include any length information, the contents of your [] in the function formal parameter list are actually ignored.
Ref : https://bit.ly/3fhlvdH
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