自定义error
1.1 系统抛
package main
import "fmt"
// 系统抛
func test01() {
a := [5]int{0, 1, 2, 3, 4}
a[1] = 123
fmt.Println(a)
//a[10] = 11
index := 10
a[index] = 10
fmt.Println(a)
}
func getCircleArea(radius float32) (area float32) {
if radius < 0 {
// 自己抛
panic("半径不能为负")
}
return 3.14 * radius * radius
}
func test02() {
getCircleArea(-5)
}
//
func test03() {
// 延时执行匿名函数
// 延时到何时?(1)程序正常结束 (2)发生异常时
defer func() {
// recover() 复活 恢复
// 会返回程序为什么挂了
if err := recover(); err != nil {
fmt.Println(err)
}
}()
getCircleArea(-5)
fmt.Println("这里有没有执行")
}
func test04() {
test03()
fmt.Println("test04")
}
func main() {
test04()
}
1.2 返回异常
package main
import (
"errors"
"fmt"
)
func getCircleArea(radius float32) (area float32, err error) {
if radius < 0 {
// 构建个异常对象
err = errors.New("半径不能为负")
return
}
area = 3.14 * radius * radius
return
}
func main() {
area, err := getCircleArea(-5)
if err != nil {
fmt.Println(err)
} else {
fmt.Println(area)
}
}
1.3 自定义error:
package main
import (
"fmt"
"os"
"time"
)
type PathError struct {
path string
op string
createTime string
message string
}
func (p *PathError) Error() string {
return fmt.Sprintf("path=%s \nop=%s \ncreateTime=%s \nmessage=%s", p.path,
p.op, p.createTime, p.message)
}
func Open(filename string) error {
file, err := os.Open(filename)
if err != nil {
return &PathError{
path: filename,
op: "read",
message: err.Error(),
createTime: fmt.Sprintf("%v", time.Now()),
}
}
defer file.Close()
return nil
}
func main() {
err := Open("/Users/5lmh/Desktop/go/src/test.txt")
switch v := err.(type) {
case *PathError:
fmt.Println("get path error,", v)
default:
}
}
输出结果:
get path error, path=/Users/pprof/Desktop/go/src/test.txt
op=read
createTime=2018-04-05 11:25:17.331915 +0800 CST m=+0.000441790
message=open /Users/pprof/Desktop/go/src/test.txt: no such file or directory