Command Line Calculator

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//Helper function for adding
int add(int a, int b){return a+b;}
//Helper function for subtracting
int subtract(int a, int b){return a-b;}
//Helper function for multiplying
int multiply(int a, int b){return a*b;}
//Helper function for dividing
int divide(int a, int b){return a/b;}



int main(int argc,char *argv[])
{
    //Create Variables
    int n1,n2;
    char op;

    //If argument counter != 4 --> wrong format // return exit-failure
    if(argc != 4){
        printf("Bitte im Format [x]_+_[y] eingeben! (Nicht x+y)\n");
        return EXIT_FAILURE;
    }

        //Initialization of variables
        n1= strtol(argv[1],NULL,10);
        n2= strtol(argv[3],NULL,10);
        op = argv[2][0];

        switch(op){
        case '+':       printf("%d + %d  = %d \n",n1,n2,add(n1,n2);
                        break;
        case '*':       printf("%d * %d  = %d \n",n1,n2,multiply(n1,n2));
                        break;
        case '-':       printf("%d - %d  = %d \n",n1,n2,subtract(n1,n2));
                        break;
        case '/':       printf("%d / %d  = %d \n",n1,n2,divide(n1,n2));
                        break;

        default:        printf("Unbekannter Operant...\n");
                        return EXIT_FAILURE;
        }



        return EXIT_SUCCESS;
}