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1、 Use to implement Error The interface way

2、 Use errors Method to build exception object

Summary  

Learning notes , Where is where .

Go The language has a built-in error interface , Exceptions can be defined by implementing interfaces , And other languages try···catch The grammar is different . I look very uncomfortable now .

Built in error The interface is as follows ：

type error interface {
    Error() string
}

1、 Use to implement Error The interface way

The sample code is as follows

package main

import "fmt"

type CustomError struct {
	code int
	msg  string
}

func (error *CustomError) Error() string {
	return fmt.Sprintf("Error -> code=%d,msg=%s\n", error.code, error.msg)
}

func test_intf(a, b int) (result int, errorMsg string) {
	if a > b {
		return a, ""
	} else {
		_error := CustomError{1, "a <= b"}
		return 0, _error.Error()
	}
}

func main() {
	result, msg := test_intf(10, 20)
	if result == 0 {
		fmt.Println(msg)
	} else {
		fmt.Printf("result = %d\n", result)
	}
}

Execution results

Error -> code=1,msg=a <= b 

Be careful

1、 Build a custom exception structure CustomError, Realization Error Method .

2、 Use errors Method to build exception object

The sample code is as follows

package main

import (
	"errors"
	"fmt"
)

var errCust = errors.New(" Custom exception ")

func test_cust(a, b int) (int, error) {
	if b == 0 {
		return 0, errCust
	}
	return a / b, nil
}

func main() {
	if res, err := test_cust(10, 0); err != nil {
		fmt.Printf("test_cust error is %v\n", err)
	} else {
		fmt.Printf("test_cust is %d\n", res)
	}
}

Execution results

test_cust error is Custom exception

Summary  

It feels like something is missing , I'll think about the learning route later , You need to stop and reflect .