Go 常见的引发 panic 的情况

1. 数组下标越界(运行时错误)

package main
import "fmt"
func main() {
    var s []string
    fmt.Println(s)
    fmt.Println(s[0])
}

运行结果：

[]
panic: runtime error: index out of range

goroutine 1 [running]:
main.main()

2. 空指针异常(运行时错误)

package main
import "fmt"
type Person struct {
    Name string
    Age  int
}
func main() {
    var p *Person
    fmt.Println(p)
    fmt.Println(p.Name)
}

运行结果：

<nil>
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x10914c8]

goroutine 1 [running]:
main.main()

3. 类型断言失败(接口转换异常)

package main
import "fmt"
func main() {
    add(20, 18)
    add(1, "hello")
}
func add(a, b interface{}) {
    i := a.(int)
    j := b.(int)
    fmt.Println(i+j)
}

运行结果：

panic: interface conversion: interface {} is string, not int
38

goroutine 1 [running]:
main.add(0x10a0f60, 0x10d6840, 0x10a1660, 0x10d6b90)

4. 通道为空，通道已关闭（写数据）

package main
func main() {
    var ch chan int
    close(ch)
}

运行结果：

panic: close of nil channel

goroutine 1 [running]:
main.main()
package main
func main() {
    var ch chan int
    ch = make(chan int,0)
    close(ch)
    ch <- 108
}

运行结果：

panic: send on closed channel

goroutine 1 [running]:
main.main()

4. 死锁，所有线程睡眠(致命错误)
   这一条是致命错误，不属于异常，但是跟异常一样，会导致程序挂掉。

package main
func main() {
    var ch chan int
    ch = make(chan int)
    ch <- 108
}

运行结果：

fatal error: all goroutines are asleep - deadlock!

goroutine 1 [chan send]:
main.main()

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