Compound literals in C

An unnamed value of struct or array type, built where it is needed.

struct Point {
    int x;
    int y;
};

static int manhattan(struct Point a, struct Point b) {
    int dx = a.x - b.x;
    int dy = a.y - b.y;
    return (dx < 0 ? -dx : dx) + (dy < 0 ? -dy : dy);
}

int distances(void) {
    int near = manhattan((struct Point){0, 0}, (struct Point){3, 4});
    int *scratch = (int[]){1, 2, 3, 4};
    return near + scratch[3];
}

How it works

1. (struct Point){1, 2} is a value, not a declaration.
2. It can be passed straight into a call.
3. Its lifetime is the enclosing block, so never return its address.

Keywords and builtins used here

• Point
• distances
• int
• manhattan
• return
• static
• struct
• void

The run, in numbers

Lines

16

Characters to type

332

Tokens

130

Three-star pace

90 tpm

At the three-star pace of 90 tokens a minute, this run takes about 87 seconds.

Type this snippet

Step 4 of 4 in Values & storage, step 30 of 35 in Language basics.

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