How to Create Composite Keys for Hash Maps in Go?

Creating Composite Keys for Hash Maps in Go

In Go, defining a composite key for a hash map involves combining multiple values to create a unique key. This technique is useful when you want to index data based on multiple parameters, such as computing and storing the value of pow(x, y) where x and y are integers.

Solution

The most straightforward approach is to create a struct that represents the composite key, incorporating the required fields:

type Key struct {
    X, Y int
}

This struct defines a key with two integer fields, X and Y, which can be used to uniquely identify each entry in the hash map:

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}])

Using this struct as the key type ensures that each entry in the map is uniquely identifiable based on the X and Y values. This allows you to retrieve the corresponding stored value efficiently using the composite key.

Important Considerations

It's crucial to note that using pointers as key types should be avoided, as they compare memory addresses instead of the actual values. Additionally, arrays can be utilized as key types, but they are less versatile than structs.

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