Function parameters

Last time, we declared a function with void test(). Today, we will pass values into one by writing parameters inside the parentheses: void test(int num1, int num2).

The values supplied by the caller are assigned to parameters with the names and types we specify. Here, those parameter names are num1 and num2.

#include <stdio.h>

void test(int num1, int num2)
{
    printf("%d %d",num1,num2);
}

int main()
{
    int number1, number2;

    scanf("%d %d",&number1,&number2);

    test(number1, number2);

    return 0;
}

The variables number1 and number2 are read in main, while the test function prints their supplied values. If we input 2 and 3, the parameters num1 and num2 receive 2 and 3. The same general idea applies to other parameter types.

Editorial correction: the original article stated that changing these parameters would also change number1 and number2 in main. That is not true for this code. The int parameters are passed by value, so the function receives copies. Modifying them does not modify the caller's variables.

The next lesson concludes this introduction to functions.