How to Get the Size (Number of Key-Value Pairs) of a Map in Go - Step by Step Examples

How to Get the Size (Number of Key-Value Pairs) of a Map in Go ?

Answer

To get the size (number of key-value pairs) of a map in Go, you can use the len() function. This function returns the number of elements in the map.

✐ Examples

1 Getting the Size of a Map Using len() Function

We can get the size of a map in Go using the len() function, which provides the number of key-value pairs in the map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the len function to get the number of key-value pairs in the map.
We store the size in a variable named mapSize.
We print the size to the console using the fmt.Println function to verify the number of key-value pairs in the map.

Go Program

package main

import "fmt"

func main() {
    // Declare and initialize a map
    myMap := map[string]int{
        "one": 1,
        "two": 2,
        "three": 3,
    }

    // Get the size of the map
    mapSize := len(myMap)

    // Print the size
    fmt.Println("Size of the map:", mapSize)
}

Output

Size of the map: 3

2 Getting the Size of an Empty Map

We can also get the size of an empty map in Go using the len() function, which returns 0 when the map is empty.

For example,

We start by declaring an empty map named emptyMap with string keys and integer values.
We use the len function to get the number of key-value pairs in the empty map.
We store the size in a variable named emptyMapSize.
We print the size to the console using the fmt.Println function to verify that the map is empty.

Go Program

package main

import "fmt"

func main() {
    // Declare an empty map
    emptyMap := make(map[string]int)

    // Get the size of the empty map
    emptyMapSize := len(emptyMap)

    // Print the size
    fmt.Println("Size of the empty map:", emptyMapSize)
}

Output

Size of the empty map: 0

3 Getting the Size of a Map After Adding Elements

We can get the size of a map in Go after adding elements using the len() function, which provides the updated number of key-value pairs in the map.

For example,

We start by declaring an empty map named dynamicMap with string keys and integer values.
We add some key-value pairs to the map using the map's index notation.
We use the len function to get the number of key-value pairs in the map after adding elements.
We store the size in a variable named dynamicMapSize.
We print the size to the console using the fmt.Println function to verify the updated number of key-value pairs in the map.

Go Program

package main

import "fmt"

func main() {
    // Declare an empty map
    dynamicMap := make(map[string]int)

    // Add elements to the map
    dynamicMap["one"] = 1
    dynamicMap["two"] = 2
    dynamicMap["three"] = 3

    // Get the size of the map after adding elements
    dynamicMapSize := len(dynamicMap)

    // Print the size
    fmt.Println("Size of the map after adding elements:", dynamicMapSize)
}

Output

Size of the map after adding elements: 3

Summary

In this tutorial, we learned How to Get the Size (Number of Key-Value Pairs) of a Map in Go language with well detailed examples.

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How to Get the Size (Number of Key-Value Pairs) of a Map in Go - Step by Step Examples