What are the error handling methods in golang?

Golang error handling methods include: 1. Return an error value. The function can return an error value as an additional return value. The return value is usually used to indicate whether the function is successfully executed; 2. Error handling function, defer mechanism , which can handle erroneous operations before the function returns; 3. panic and recover, which can stop the program immediately and perform corresponding error handling; 4. Custom error types, with more information and functions, can use type assertions to Get error details and more.

The operating environment of this article: Windows 10 system, Go1.20.4 version, Dell G3 computer.

Golang is an open source programming language developed by Google. It has some unique features and methods in error handling. The following are several common ways of error handling in Golang:

Return error value: In Golang, the return value is usually used to indicate whether the function was executed successfully. Functions can return an error value as an additional return value. This error value is usually a type that implements the error interface. If the function executes successfully, nil is returned; if the function fails, a non-empty error value is returned.

For example:

func Divide(a, b float64) (float64, error) {
    if b == 0 {
        return 0, errors.New("division by zero")
    }
    return a / b, nil
}

When calling this function, you can determine whether the function is executed successfully by checking the error value returned. If the error value is nil, it means that the function execution is successful; otherwise, it means that the function execution fails, and corresponding error processing can be performed based on the error value.

Error handling function: Golang provides a mechanism called defer that can perform some cleanup operations, including handling errors, before the function returns. You can use the defer keyword to define an error handling function that will be called before the function returns.

For example:

func readFile() error {
    file, err := os.Open("file.txt")
    if err != nil {
        return err
    }
    defer file.Close()
    // 读取文件的操作
    // ...
    return nil
}

In the above example, the defer keyword is used to close the file before the function returns. This ensures that the file is always closed before the function returns, regardless of whether an error occurred within the function.

panic and recover: Golang provides two built-in functions, panic and recover, for handling serious error situations. When a program encounters an error that prevents it from continuing to run, the panic function can be used to cause a panic, causing the program to stop executing immediately. You can then use the recover function to capture the panic in the defer function and handle the error accordingly.

For example:

func divide(a, b float64) float64 {
    if b == 0 {
        panic("division by zero")
    }
    return a / b
}
func main() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("Recovered from panic:", r)
        }
    }()
    result := divide(10, 0)
    fmt.Println("Result:", result)
}

In the above example, if the divisor is 0, a panic will be triggered. Use the recover function in the defer function to capture panics and print out panic information. This prevents the program from crashing and handles panics accordingly.

Custom error types: In addition to using the built-in error interface to represent errors, Golang also allows you to define your own error types. Custom error types can have more information and functionality to meet specific error handling needs.

For example:

type MyError struct {
    message string
    code    int
}
func (e MyError) Error() string {
    return fmt.Sprintf("%s (code: %d)", e.message, e.code)
}
func sqrt(n float64) (float64, error) {
    if n < 0 {
        return 0, MyError{"negative number", 100}
    }
    // 计算平方根的操作
    // ...
    return math.Sqrt(n), nil
}

In the above example, a custom error type MyError is defined, which contains the error message and error code. In the function sqrt, if the input value is a negative number, a MyError type value containing error information and error code is returned. When calling this function, you can use type assertions to get specific information about the error.

Summary

Golang’s error handling methods include returning error values, error handling functions, panic and recover, and custom error types. These methods can be selected and used according to specific needs and scenarios.

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