objective-c - What does it mean when you declare a variable with two sets of square brackets?

Question

I've just came across something like

float a[4][5];

I know one pair of square brackets after a variable declares it as a C-array, but what does two pairs do?

Answer 1

那是一个具有 4 列和 5 行浮点数的二维 C 数组。您可以通过 a[x][y] 访问各个值。