How Can I Efficiently Retrieve a Slice of Keys from a Go Map?

Retrieving a Slice of Keys from a Go Map

To retrieve a slice of keys from a Go map, you can iterate over the map and manually copy the keys to a slice. This approach is concise, but requires additional memory allocation and unnecessary copying.

A more efficient alternative that eliminates reallocations is to directly assign members of the slice within the range loop:

keys := make([]int, len(mymap))

for i, k := range mymap {
    keys[i] = k
}

By specifying the capacity of the slice in advance, you avoid the overhead of reallocation while preserving the ability to add or remove keys. This approach is more efficient, especially for large maps.

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