How to judge errors in Golang

Golang is a very popular programming language that has the advantages of efficiency, concurrency, reliability, and simplicity. In Golang, we often need to handle and judge errors. So, how to make error judgment in Golang?

Error Type

In Golang, errors are a very common type. In the built-in error interface, it has a method Error() string, which is used to return an error string. At the same time, we can also customize an error type and only need to implement the error interface. For example:

type MyError struct {
  Msg string
  File string
  Line int
}

func (e *MyError) Error() string {
  return fmt.Sprintf("%s:%d %s", e.File, e.Line, e.Msg)
}

In this way, we define a MyError type, which implements the error interface. We can define our own error types according to actual needs.

Error handling

In Golang, error handling is usually judged using if statements. For example:

f, err := os.Open("test.txt")
if err != nil {
  log.Fatal(err)
}

In the above code, we use the Open function in the os package to try to open a file. If an error occurs, a non-nil error object will be returned. At this time, we can use the if statement to make a judgment. If the error object is not nil, we can output error information.

In actual development, we may need to judge multiple errors. At this point, we can use the switch statement to make a judgment. For example:

switch e := err.(type) {
case *MyError:
  fmt.Println("my error occurred:", e.Msg)
default:
  fmt.Println("unknown error occurred:", err)
}

In the above code, we use the switch statement to determine the error type. If an error of type MyError occurs, we can output the corresponding error message.

Related functions

In Golang, there are also some functions related to error handling. For example:

• panic: used to raise errors and used in abnormal situations.
• recover: Used to capture errors caused by panic and resume program execution.
• fmt.Errorf: Returns a new error object.

Summary

In Golang, error handling is a very important part. Correct error handling can ensure that the program can continue to run and output relevant error information even if an exception occurs. In actual development, error handling and judgment should be carried out according to the actual situation. At the same time, attention should also be paid to the customization of error types and the use of related functions.

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