reflect.NumMethod() Function in Golang with Examples

Go language provides inbuilt support implementation of run-time reflection and allowing a program to manipulate objects with arbitrary types with the help of reflect package. The reflect.NumMethod() Function in Golang is used to get the number of exported methods in the value’s method set. To access this function, one needs to imports the reflect package in the program.

Syntax:

func (v Value) NumMethod() int

Parameters: This function does not accept any parameter.

Return Value: This function returns the number of exported methods in the value’s method set.

Below examples illustrate the use of the above method in Golang:

Example 1:

// Golang program to illustrate
// reflect.NumMethod() Function

package main

import (
    "fmt"
    "reflect"
)

type gfg struct {
    Prop string
}

func (f gfg) Geek1() string {
    return f.Prop
}

func (f gfg) Geek2() {
}

// Main function
func main() {
    fooType := reflect.TypeOf(gfg{})
    for i := 0; i < fooType.NumMethod(); i++ {
        method := fooType.Method(i)
        fmt.Println(method.Name)
    }
}

Output:

Geek1
Geek2

Example 2:

// Golang program to illustrate
// reflect.NumMethod() Function

package main

import (
    "log"
    "reflect"
)

type Reindeer string

func (r Reindeer) TakeOff() {
    log.Printf("%q lifts off.", r)
}

func (r Reindeer) Land() {
    log.Printf("%q gently lands.", r)
}

func (r Reindeer) ToggleNose() {
    if r != "rudolph" {
        panic("invalid reindeer operation")
    }
    log.Printf("%q nose changes state.", r)
}

func main() {
    r := Reindeer("rudolph")

    t := reflect.TypeOf(r)

    for i := 0; i < t.NumMethod(); i++ {
        m := t.Method(i)
        log.Printf("%s", m.Name)
    }
}

Output:

2009/11/10 23:00:00 Land
2009/11/10 23:00:00 TakeOff
2009/11/10 23:00:00 ToggleNose