Pointers

The use of pointers is very important in C and an essential concept to grasp. My code below with comments helps to explain the fundamentals of declaring integers, pointers and assigning valuables through pointers and passing pointers to functions.

#include <stdio.h>

//  Declaration of function

void myFunction(int *ptr, int *ptr2);

int main(int argc, const char * argv[])
{
    // Declare two variables

    int a=0;
    int b=0;

    // Declare two pointers

    int *ptr;
    int *ptr2;

    // Point the pointers at the variables

    ptr = &a;
    ptr2 = &b;

    // Call the function and pass the pointers to it

    myFunction(ptr, ptr2);

    // Print the values assigned by the function

    printf("Hello, World! %d %d\n", *ptr2, *ptr);
    return 0;
}

void myFunction(int *pointer1, int *pointer2)
{
    // Assign values to the variables pointed at
    // by the pointers passed to this function
    // Note the pointers passed (ptr and ptr2) don't
    // have to be the same name as the pointers in
    // function, just the same type. In this case ints.

    *pointer1 = 8;
    *pointer2 = 12;
}

I have written a more in depth post on pointers as it is such an important topic. For this later post please see here