Go - (7) Maps

Maps A collection of key-value pairs You can initialize maps like below. students := make(map[string]int) students["SE"] = 100 students["BA"] = 73 students["DA"] = 49 ages := map[string]int { "Bella": 17, "Edward": 18, } To get the number of key-value pairs in the map, use the len () function. Searching for a value in a map using its key is much faster than searching a slice. You should search the index by index in a slice until you find the value. Syntaxes of Maps insert a value: mapName[key] = value get a value: value = mapName[key] delete a value: delete(mapName, key) check if a key exists: value =, ok := mapName[key] Any type can be used as map values, but not as map keys. Keys should be comparable types (numeric, string, bool, channel, pointer, and interface). So, types like slice or array cannot be used as map keys. If you try to access a nil map, the code panics. If you try to access a value where the key doesn't exist, the code returns the zero value. You can't have duplicate keys. A key can have a maximum of one value assigned to it. If you pass a map to a function and update its elements inside the function, the content of the original map is changed.

Apr 27, 2025 - 03:36

Maps

A collection of key-value pairs

You can initialize maps like below.

    students := make(map[string]int)
    students["SE"] = 100
    students["BA"] = 73
    students["DA"] = 49

    ages := map[string]int {
        "Bella": 17,
        "Edward": 18,
    }

To get the number of key-value pairs in the map, use the len () function.

Searching for a value in a map using its key is much faster than searching a slice. You should search the index by index in a slice until you find the value.

Syntaxes of Maps

insert a value: mapName[key] = value
get a value: value = mapName[key]
delete a value: delete(mapName, key)
check if a key exists: value =, ok := mapName[key]

Any type can be used as map values, but not as map keys. Keys should be comparable types (numeric, string, bool, channel, pointer, and interface). So, types like slice or array cannot be used as map keys.

If you try to access a nil map, the code panics.
If you try to access a value where the key doesn't exist, the code returns the zero value.
You can't have duplicate keys. A key can have a maximum of one value assigned to it.
If you pass a map to a function and update its elements inside the function, the content of the original map is changed.