Detailed explanation of how to handle errors in Golang

Golang (or Go) is a fast programming language developed by Google and designed to improve programmer productivity. Golang has some built-in syntax features that allow programmers to quickly develop efficient applications. However, error handling is an unavoidable part of any programming language, so how to handle errors in Golang?

Error handling refers to how the program should handle these errors when errors occur in the program. In Golang, error handling is a little different from other languages. First of all, there are no exceptions in Golang similar to those in Java or C#. Instead, the return statement is used to return error information. Secondly, error handling in Golang is usually used together with the defer statement to ensure the correct release of resources.

The concept of errors in the Go language is provided by the built-in error type. In Golang, the error type can be used like other types. This means that the function can return a value of type error, indicating that an error occurred while executing the function. If there are no errors, returns nil.

The following is a simple function that returns the average of three integers and returns an error if one of the numbers is negative.

func average(x, y, z float64) (float64, error) {
    if x < 0 || y < 0 || z < 0 {
        return 0, errors.New("Negative number(s) contained")
    }
    return (x + y + z) / 3, nil
}

As you can see, if any number is less than 0, the function will return an error, which is created by the errors.New function and returns a string representing the error information. If there are no errors, the function returns the mean and nil.

In the main function, we can use this function and handle the returned error. Below is an example of using this function and handling errors.

func main() {
    result, err := average(90, -3, 50)
    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println(result)
    }
}

In this example, we will use the average function to calculate the average of three numbers. Since -3 is a negative number, we expect the function to return an error. If there is an error, the error will be printed on the console, otherwise the result will be printed. In actual programming, error handling should be more complex.

In addition, as mentioned earlier, error handling in Golang is usually used with the defer statement. The defer statement is used to handle the correct release of resources before the function returns. This ensures that the resources are released correctly, regardless of whether the function returns an error. Here is a more complete example using the defer statement:

func readFile() error {
    file, err := os.Open("filename.ext")
    if err != nil {
        return err
    }
    defer file.Close()

    // Read contents of file...
}

func main() {
    err := readFile()
    if err != nil {
        fmt.Println(err)
    }
}

In this example, we open a file and read its contents. Because the file.Close() statement is executed before the function returns, the file will be closed correctly no matter what error occurs.

In short, in Golang, the basic concept of error handling is the same as in other languages. Programmers should ensure that any errors that may occur are properly handled before the function returns. Using the built-in error type combined with the defer statement can facilitate error handling.

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