Arrays Demo code

/* A demo of arrays and some of the
   fiddly details
   
   Marc Chee (cs1511@cse.unsw.edu.au), March 2021
*/

#include <stdio.h>

void print_array(int array[], int length);

int main(void) {
    // Different ways of initialising an array
    // ---------------------------------------
    
    // 1. All zeroes
    int array_1[10] = {};
    
    // 2. The exact numbers given {exactly the same number of elements}
    int array_2[10] = {1,2,3,4,5,6,7,8,9,10};
    
    // 3. The numbers, then zeroes. Anything not specified after the
    //    {given numbers} is made into zero
    int array_3[10] = {1,2,3};
    
    // 4. Not initialised . . . can't be used
    int array_4[10];
    
    print_array(array_1, 10);
    print_array(array_2, 10);
    print_array(array_3, 10);
    // Careful! Using uninitialised memory is very dangerous
    // We have no idea what it will be
    //print_array(array_4, 10);
    
    // Some array usage demos
    // ----------------------
    
    // declare an array, all zeroes
    int student_marks[10] = {};

    // make first element 85
    student_marks[0] = 85;
    // access using a variable
    int access_index = 3;
    student_marks[access_index] = 50;
    // copy one element over another
    student_marks[2] = student_marks[6];
    // cause an error by trying to access out of bounds
    student_marks[10] = 99;

}

// A function for printing an array of integers
// Assumes that length is <= the size of the array
// and will print the first length elements on a
// line separated by spaces
void print_array(int array[], int length) {
    int i = 0;
    while (i < length) {
        printf("%d ", array[i]);
        i++;
    }
    printf("\n");
}