Changing Elements

You can also change an element of an array. Write the array's name and the index in square brackets, just like when you read an element, and assign a new value with =, as you would to a variable:

int scores[] = {80, 92, 75, 60, 88};
scores[2] = 79;
printf("%d %d %d\n", scores[1], scores[2], scores[3]);

This prints:

92 79 60

The element at index 2 now has the value 79, and the old 75 is gone. Nothing was inserted or moved: the array still has five elements, and the others stayed the same.

Make sure you don't write == instead of =. The statement scores[2] == 79; only compares the two values and changes nothing. You don't get any error message: the program runs, and the element just keeps its old value.

An element behaves like a variable of its type, so +=, -=, ++ and -- work with it too. In a game, three players start with three lives each:

int lives[] = {3, 3, 3};
lives[0]--;
lives[2] += 2;
printf("%d %d %d\n", lives[0], lives[1], lives[2]);

This prints:

2 3 5

lives[0]--; took one life from the first player, and lives[2] += 2; gave the third player two extra lives. The second player still has three.