Arrays

An array lets you group multiple values under one name. Declaring a separate variable for every value quickly makes a program cumbersome, so arrays are a useful way to organize repeated data.

In a declaration such as int arr[10], arr is the array name and 10 is the number of elements. The size goes inside square brackets.

Read and print three elements

#include <stdio.h>

int main()
{
    int arr[3];

    scanf("%d%d%d",&arr[0],&arr[1],&arr[2]);
    printf("%d %d %d",arr[0],arr[1],arr[2]);

    return 0;

}

This array stores three integers. Array indices begin at zero, so the three elements are arr[0], arr[1], and arr[2]. The program reads a value into each one and then prints them using the same indices.

Use a loop

Writing out every element becomes impractical when an array has hundreds or thousands of values. We can use the loops from the previous lessons instead:

#include <stdio.h>

int main()
{
    int arr[10];

    for(int i=0;i<10;i++)
    {
        scanf("%d",&arr[i]);
    }

    for(int j=0;j<10;j++)
    {
        printf("%d",arr[j]);
    }
    return 0;
}

This example uses ten elements so it is easy to test by hand. The first for loop reads the values in order, and the second prints them.

Translation note: the indices in this example are 0 through 9, not 0 through 10 as the original closing sentence implied. The declared size is ten, and both loops use < 10.