Learn the Go language functions tutorial

This article illustrates the basic usage of Go language functions. I will share it with you for your reference as follows:

So I'm going to say 1 is the Go function is different from 1 in some other language

1 function format is different

func GetMsg(i int) (r string) {

    fmt.Println(i)

    r = "hi"

    return r

}

func says that this is a function

GetMsg is the function name

The (i int) function receives one int parameter

The (r string) function returns a value of type string

The 2 function can return multiple return values

This is different from c, php, and lua

func GetMsg(i int) (r string, err string) {

    fmt.Println(i)

    r = "hi"

    err = "no err"

    return r,err

}

3 use of defer

defer means "call when a function exits", especially when reading or writing to a file. close is called after open, and close is used by defer

func ReadFile(filePath string)(){

    file.Open(filePath)

    defer file.Close()

    if true {

        file.Read()

    } else {

        return false

    }

}

This means that instead of calling close immediately after file.Open, file.Close () is called when return false is called. This effectively avoids memory leaks in the C language.

4. Difficult to understand: panic, recover and defer

So defer is very clear.

Panic and Recover, we think of them as throw and catch in other languages

Here's an example:

package main

import "fmt"

func main() {

    f()

    fmt.Println("Returned normally from f.")

}

func f() {

    defer func() {

        if r := recover(); r != nil {

            fmt.Println("Recovered in f", r)

        }

    }()

    fmt.Println("Calling g.")

    g(0)

    fmt.Println("Returned normally from g.")

}

func g(i int) {

    if i > 3 {

        fmt.Println("Panicking!")

        panic(fmt.Sprintf("%v", i))

    }

    defer fmt.Println("Defer in g", i)

    fmt.Println("Printing in g", i)

    g(i + 1)

}

Returned:

Calling g.

Printing in g 0

Printing in g 1

Printing in g 2

Printing in g 3

Panicking!

Defer in g 3

Defer in g 2

Defer in g 1

Defer in g 0

Recovered in f 4

Returned normally from f.

Panic throws the information and jumps out of the function. Recover receives the information and continues to process it.

If you understand this example, you will have a basic understanding of Recover and Panic

I hope this article has been helpful to you in the programming of Go language.