Function pointers in C

A function's name is an address, so it can be stored, passed and called.

static int add(int a, int b) {
    return a + b;
}

static int multiply(int a, int b) {
    return a * b;
}

int apply(int (*op)(int, int), int a, int b) {
    return op(a, b);
}

int dispatch(int which, int a, int b) {
    int (*table[2])(int, int) = {add, multiply};
    if (which < 0 || which > 1) {
        return 0;
    }
    return table[which](a, b);
}

How it works

1. int (*op)(int, int) is a pointer to such a function.
2. The name alone is enough; the ampersand is optional.
3. A table of them replaces a long switch.

Keywords and builtins used here

• add
• apply
• dispatch
• if
• int
• multiply
• return
• static

The run, in numbers

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Tokens

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Step 2 of 4 in Generic & function pointers, step 7 of 25 in Pointers & memory.

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