Storage classes in C

static, extern and automatic: where a variable lives and how long it lasts.

static int call_count = 0;

static int next_id(void) {
    static int id = 100;
    call_count++;
    return id++;
}

int ids_taken(void) {
    return call_count;
}

int take_three(int *out) {
    for (int i = 0; i < 3; i++) {
        out[i] = next_id();
    }
    return ids_taken();
}

How it works

1. A static local keeps its value between calls.
2. A static function or global is private to its translation unit.
3. extern declares something defined in another file.

Keywords and builtins used here

• for
• ids_taken
• int
• next_id
• return
• static
• take_three
• void

The run, in numbers

Lines

18

Characters to type

250

Tokens

79

Three-star pace

90 tpm

At the three-star pace of 90 tokens a minute, this run takes about 53 seconds.

Type this snippet

Step 2 of 7 in Functions, step 16 of 35 in Language basics.

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