(PCC)::[how-to-write-a-C-Program-to-Check-Prime-or-Armstrong-Number-Using-User-defined-Function]::[c]
//Check Prime and Armstrong Number #include <math.h> #include <stdio.h> int checkPrimeNumber(int n); int checkArmstrongNumber(int n); int main() { int n, flag; printf("Enter a positive integer: "); scanf("%d", &n); // check prime number flag = checkPrimeNumber(n); if (flag == 1) printf("%d is a prime number.\n", n); else printf("%d is not a prime number.\n", n); // check Armstrong number flag = checkArmstrongNumber(n); if (flag == 1) printf("%d is an Armstrong number.", n); else printf("%d is not an Armstrong number.", n); return 0; } int checkPrimeNumber(int n) { int i, flag = 1; for (i = 2; i <= n / 2; ++i) { // condition for non-prime number if (n % i == 0) { flag = 0; break; } } return flag; } int checkArmstrongNumber(int num) { int original, rem, n = 0, flag; double result = 0.0; original = num; while (original != 0) { original /= 10; ++n; } original = num; while (original != 0) { rem = original % 10; result += pow(rem, n); original /= 10; } // condition for Armstrong number if (round(result) == num) flag = 1; else flag = 0; return flag; }