This program calculates the the factorial of an integer number entered by the user. The function uses for loop to calculate the factorial and returns the number. Program terminates if a non integer number is entered. This C language program uses for loop in just a single statement to calculates the factorial of integer number.

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#include 

int fact(int n);

int main(void) {
  int current;

  printf("Enter a positive integer [to terminate enter non-positive] > ");
  scanf("%d", &t);
  while (current > 0) {
    printf("The factorial of %d is %d\n", current, fact(current));
    printf("Enter a positive integer [to terminate enter non-positive] > ");
    scanf("%d", &t);
  }
}

/* n is a positive integer. The function returns its factorial */
int fact(int n) {
  int lcv;    /* loop control variable */
  int p;      /* set to the product of the first lcv positive integers */

  for(p=1, lcv=2; lcv <= n; p=p*lcv, lcv++);
  return p;
}