Match

C programmers often first read match as a stricter switch.

That comparison helps at the beginning, but it is incomplete. C switch mainly branches on integer values. If the state also carries data, you still manually read fields from a struct or union.

Rust match performs pattern matching:

check what shape a value has, and bind the data inside that shape.

Earlier, when discussing enum, we used Rust enums as a safer replacement for C tagged unions. This article continues from there: how match handles richer state, references, conditions, and local unpacking.

In C, enum and union often appear together. The enum says which kind of value is active, and the union reuses the same storage for different payloads:

enum ValueKind {
    VALUE_INT,
    VALUE_FLOAT,
    VALUE_TEXT,
};

struct Value {
    enum ValueKind kind;
    union {
        int i;
        float f;
        const char *text;
    } data;
};

This is a tagged union. It is common and useful, but correctness depends on discipline:

if (value->kind == VALUE_INT) {
    printf("%d\n", value->data.i);
}

If kind is VALUE_TEXT and the code reads data.i, the C type system does not stop it. In Rust, this shape is usually represented with enum, where the tag and the data live in one type.