Scope & Storage

Local vs global

A local variable is declared inside a function and only exists while that function runs. A global variable is declared outside every function and is visible everywhere in the file.

static keeps its value

A static local variable is initialised once and remembers its value between calls, unlike a normal local variable.

void counter(void) {
    static int count = 0;
    count++;
    printf("%d\n", count);
}

// counter(); counter(); counter();
// prints 1, 2, 3

Output:

1
2
3

Quick check: What happens to a normal (non-static) local variable when its function returns?

• It keeps its value for next call
• It is destroyed
• It becomes global