SVN / public / code / vorlesung-01 / PrimeMain.cpp

// Copyright 2026, University of Freiburg
// Chair of Algorithms and Data Structures
// Author: Hannah Bast <bast@cs.uni-freiburg.de>

#include <cstdio>
#include <cstdlib>

#include "./Prime.cpp"

// Main function.
int main(int argc, char **argv) {
  // Parse command-line arguments.
  if (argc != 2) {
    printf("Usage: ./Prime <number>\n");
    exit(1);
  }
  int n = atoi(argv[1]);

  // If the number is prime, say so, otherwise output the smallest divisor
  // greater than 1.
  int i = isPrime(n);
  if (i == 0) {
    printf("Congratulations, %d is prime!\n", n);
  } else {
    printf("I am very sorry, %d is not prime; as a consolation, "
           "here is the smallest non-trivial divisor: %d\n",
           n, i);
  }
}