golang panic standard error

Panic is an exception handling mechanism in the golang programming language. When the program encounters a fatal error, it will use the panic function to trigger a panic and immediately stop program execution. This article will introduce the concept of panic and how to deal with panic.

1. The concept of Panic
   In golang, the panic triggered by the panic function is a very powerful mechanism that can cause the program to stop execution and report an error. After a panic occurs, golang will release all allocated resources (memory, file handles, etc.), and the stack will be traced back and panic information will be displayed until the program ends or is intercepted by the recover function.

The following is a simple sample program, you can try the effect of the panic function yourself:

package main

func main() {
    panic("出错了")
}

Here, we explicitly call the panic function and change the string "Error ” is passed to it as a parameter. The program will stop running immediately here, and the output is as follows:

panic: 出错了

goroutine 1 [running]:
main.main()
        /tmp/sandbox657484611/main.go:4 +0x2a

2. panic’s error message
   Usually, when we use the panic function, we try to provide some easy-to-understand error messages so that we can Find and resolve problems faster when they arise. In the panic function, you can pass it a string or error, which can be displayed in the stack trace.

The following is a sample program. We use error:

package main

import (
    "errors"
)

func main() {
    err := errors.New("这里出错了")
    panic(err)
}

After running, we will see the following output in the terminal window:

panic: 这里出错了

goroutine 1 [running]:
main.main()
        /tmp/sandbox633080144/main.go:7 +0x2f

As you can see from the above output, we successfully displayed the customized error message in panic.

3. Handling of panic
   In programs, we usually use structures such as try-catch or try-finally to handle exceptions. In golang, panic and recover can be used together to handle exceptions.

The recover function is a built-in function that can be used in the defer function. We can resume the execution of the program when a panic occurs, so that the entire program does not crash, and we can get the panic error message.

The following is an example of using panic and recover together:

package main

import "fmt"

func main() {
    defer func() {
        r := recover()
        if r != nil {
            fmt.Println("发生了 panic:", r)
        }
    }()

    panic("出错了")
}

In this program, we use a defer function. The defer function will be executed before the end of the current code block, so we You can perform recovery operations when the program panics.

In the recover function, we store the panic error messages and display them in the terminal. Running this sample program, we can see the following output:

发生了 panic: 出错了

In the above sample program, we triggered the panic function and used the recover function in defer to recover. Execute the recover function in defer to capture panic. If a panic occurs, it can be handled in defer function.

In short, in golang, panic can easily handle exceptions in the program flow. The panic mechanism can record the stack trace information of each Go program and then use this information to report errors. It should be noted that although the panic mechanism is very powerful, it should be used with caution in actual programming to avoid affecting the overall stability of the program.

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