Take a number as input and reverse the number.
  #include <stdio.h>

int main(void)
{
long int num, rev = 0, onum;

printf("\nEnter number : ");
scanf("%ld", &num);

onum = num;

do
{
rev = (rev * 10) + (num % 10);
num /= 10;
}while(num > 0);

printf( "\nReverse of %ld is %ld", onum, rev);

return 0;
}