User-Defined Functions

Write a program in C to reverse a number entered by user using the concept of function with return type and arguments.

Write a program to find the reverse of a number [Suppose $N$]. The program must take value of $N$ from main(), find the reverse of $N$ from user-defined function named FindRev() and display the reverse of $N$ from the main(). Write the output of following program and explain the result with reference to the concept of the storage class.

#include<stdio.h>
int main(){
static int a=5;
printf("Value of a is: %d\n",a);
a=a+10;
if(a<20)
main();
return 0; }

Write a program in C to check happy number entered by user using the concept of function with return type and no arguments [Hint: Happy number is a number for which the sum of the squares of the digits eventually equals 1. For example, 203 is happy because $2^{2} + 0^{2} + 3^{2} = 13$; $1^{2} + 3^{2} = 10$; $1^{2} + 0^{2} = 1$].