How to find the Length of Channel, Pointer, Slice, String and Map in Golang?

In Golang, len function is used to find the length of a channel, pointer, slice, string, and map.

Channel: In Go language, a channel is a medium through which a goroutine communicates with another goroutine and this communication is lock-free.

// Go program to illustrate
// how to find the length a channel
package main

import "fmt"

func main() {

    // Creating a channel using make() function
    ch:= make(chan int, 5)
    fmt.Printf("\nChannel: %d", len(ch))
    ch <- 0
    ch <- 1
    ch <- 2
    fmt.Printf("\nChannel: %d", len(ch))
}

Output:

Channel: 0
Channel: 3

Pointer: Pointers in Go programming language or Golang is a variable which is used to store the memory address of another variable.

// Go program to illustrate
// how to find the length a Pointer.
package main

import "fmt"

func main() {

    // Creating a pointer
    var poin *[10]string
    fmt.Printf("\nPointer: %d", len(poin))
}

Output:

Pointer: 10

Slice: Slice is a variable-length sequence which stores elements of a similar type, you are not allowed to store different type of elements in the same slice.

// Go program to illustrate
// how to find length Slice
package main

import "fmt"

func main() {

    // Creating a slice using make() function
    sliceEx := make([]int, 10)
    fmt.Printf("\nSlice: %d", len(sliceEx))
}

Output:

Slice: 10

String: It is a sequence of variable-width characters where each and every character is represented by one or more bytes using UTF-8 Encoding.

// Go program to illustrate
// how to find length a String.
package main

import "fmt"

func main() {
    // Creating a string
    strEx := "India"
    fmt.Printf("\nString: %d", len(strEx))
}

Output:

String: 5

Map: Golang Maps is a collection of unordered pairs of key-value.

// Go program to illustrate
// how to find length a Map.
package main

import "fmt"

func main() {

    // Creating a map using make() function
    mapEx := make(map[string]int)
    mapEx["A"] = 10
    mapEx["B"] = 20
    mapEx["C"] = 30
    fmt.Printf("\nMap: %d", len(mapEx))
}

Output:

Map: 3