defer and panic of golang function

The defer and panic keywords are used to control exceptions and post-processing: defer: push the function onto the stack and execute it after the function returns. It is often used to release resources. Panic: throws an exception to interrupt program execution and is used to handle serious errors that cannot continue running. The difference: defer is only executed when the function returns normally, while panic is executed under any circumstances, even if an error occurs.

defer and panic of Go function

defer and panic are powerful keywords in Go, which can realize exception and post-processing Fine-grained control of configuration processing.

#defer

defer keyword is used to execute the specified function before the function returns. It pushes the function onto a stack and executes it after the function returns. defer is often used to release resources when a function exits, such as closing a file or network connection.

Grammar:

defer func() {...}

Practical case:

func OpenFile() {
    file, err := os.Open("myfile.txt")
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close() // 文件将在 OpenFile 返回后立即关闭
}

panic

The panic keyword is used to interrupt the program when an unrecoverable error occurs. It throws an exception, causing the function and all functions that call it to stop executing. Panic is usually used to deal with serious errors, such as errors that prevent the program from continuing to run.

Grammar:

panic(any)

Practical case:

func ValidateUser(username, password string) {
    if username == "" {
        panic("用户名不能为空") // 抛出一个 panic，因为用户名不能为空
    }
    // ...
}

The difference between defer and panic

• defer is only executed when the function returns normally, while panic is executed in any case, even if an error occurs.
• defer can be used to clean up resources or perform other post-processing operations, while panic is used to terminate program execution.

Best Practices

• Use defer to handle resource cleanup or other required operations, even if an error occurs.
• Use panic to handle serious errors, such as errors that prevent the program from continuing to run.
• Avoid overusing panic, as it can cause the program to terminate unexpectedly.

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