How to check function return value in golang?

To check Go language function return value elegantly, you can use the following two methods: Use error value: This is a common method of handling errors. If the function returns a non-nil value, it means an error occurred. Use multiple return values: When a function needs to return multiple values, multiple return values ​​can be used. The first return value is usually the main value, and subsequent return values ​​can be used for error handling or other information.

How to elegantly check the function return value in Go language

In Go language, a function can return multiple values ​​by to return errors or other information. It is important to check these values ​​to make sure they are as expected. Here are two common ways to check function return values:

1. Using error values

This is the most common way to handle errors. The error type is a built-in type that indicates that an error has occurred when a function returns a non-nil value.

func someFunction() error {
    // 执行一些操作
    if err != nil {
        return err
    }
}

func main() {
    err := someFunction()
    if err != nil {
        // 处理错误
    }
}

2. Use multiple return values

When a function needs to return multiple values, you can use multiple return values. The first return value is usually the main value, and subsequent return values ​​can be used for error handling or other information.

func someFunction() (string, error) {
    // 执行一些操作
    if err != nil {
        return "", err
    }
    return "成功", nil
}

func main() {
    value, err := someFunction()
    if err != nil {
        // 处理错误
    }
}

Practical case

Let us consider a file reading example where the return value of a function needs to be checked:

import (
    "fmt"
    "io/ioutil"
    "os"
)

func readFile(filename string) ([]byte, error) {
    return ioutil.ReadFile(filename)
}

func main() {
    data, err := readFile("myfile.txt")
    if err != nil {
        if os.IsNotExist(err) {
            fmt.Println("文件不存在")
        } else {
            fmt.Printf("读取文件时出错: %v", err)
        }
        return
    }
    fmt.Println(string(data))
}

In this example, ## The #readFile function uses an error value to indicate file read errors. In the main function we check for errors and take different actions depending on the error type.

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