How can I effectively use structs to create composite keys in Go maps?

Using Structs for Composite Keys in Go Maps

In Go, composite keys in hash maps allow combining multiple values to form a unique key for the map. Unlike composite keys in databases, these are used for computational purposes.

To store computed values of pow(x, y) in a hash table, you can define a composite key using a struct:

type Key struct {
    X, Y int
}

This struct combines the x and y values to create a key. You can use this key in a map as follows:

m := map[Key]int{}
m[Key{2, 2}] = 4
m[Key{2, 3}] = 8

fmt.Println("2^2 =", m[Key{2, 2}])
fmt.Println("2^3 =", m[Key{2, 3}])

Output:

2^2 = 4
2^3 = 8

Structs are used as keys because they provide a simple way to represent multiple values as a single unit. They ensure proper comparison operators (== and !=) are defined, allowing efficient key retrieval from the map.

Using pointers as key types is not recommended, as pointer comparison only checks memory addresses rather than the actual values. Arrays can also be used as key types, but structs offer more flexibility.

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