44 lines
1.2 KiB
Go
44 lines
1.2 KiB
Go
// Maps are Go's built-in associative data type (sometimes
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// called "hashes" or "dicts" in other languages).
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package main
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import "fmt"
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func main() {
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// To create an empty map, use the builtin `make`:
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// `make(map[key-type]val-type)`.
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m := make(map[string]int)
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// Set key/value pairs using typical `name[key] = val`
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// syntax.
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m["k1"] = 7
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m["k2"] = 13
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// Printing a map with e.g. `Println` will show all of
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// its key/value pairs, which can be useful for
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// debugging.
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fmt.Println("map:", m)
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// Get a value for a key with `name[key]`.
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v1 := m["k1"]
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fmt.Println("v1: ", v1)
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// The builtin `len` function returns the number of
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// key/value pairs when called on a map.
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fmt.Println("len:", len(m))
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// The builtin `delete` removes key/value pairs from
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// a map
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delete(m, "k2")
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fmt.Println("map:", m)
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// The optional second return value when getting a
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// value from a map indiciates if the key was present
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// in the map. This can be used to disambiguate
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// between missing keys and keys with zero values
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// like `0` or `""`.
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_, prs := m["k2"]
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fmt.Println("prs:", prs)
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}
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