对不同状态的channel操作会出现的情况

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var ch chan int    // 定义nil channel
value, ok := <-ch
// 阻塞: fatal error: all goroutines are asleep - deadlock!

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ch := make(chan int, 10)
for i := 0; i < 10; i++ {
	ch <- i
}
close(ch)
for v := range ch {
	fmt.Printf("v: %v|", v)
}
// 输出值: v: 0|v: 1|v: 2|v: 3|v: 4|v: 5|v: 6|v: 7|v: 8|v: 9|

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ch := make(chan int)
value, ok := <-ch
// 阻塞: fatal error: all goroutines are asleep - deadlock!

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ch := make(chan int,1)
close(ch)
val, ok := <-ch
fmt.Printf("val: %v, ok: %v\n", val, ok) // val: 10, ok: true
val, ok = <-ch
fmt.Printf("val: %v, ok: %v\n", val, ok) // val: 0, ok: false

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ch := make(chan<- int, 1)
ch <- 1
x := <-ch // 编译错误: invalid operation: cannot receive from send-only channel ch (variable of type chan<- int)
fmt.Println(x)

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var ch chan int  // 定义一个空的管道
ch <- 1          // 尝试向管道写入数据
// 阻塞：fatal error: all goroutines are asleep - deadlock!

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var ch = make(chan int, 10)   // 定义一个有 10 个元素的管道
// 尝试填满管道
for i:=0; i < 10; i++ {
    ch <- i
}
ch <- 11                     // 尝试向管道写入第11个元素
// 阻塞：fatal error: all goroutines are asleep - deadlock!

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var ch = make(chan int, 10)  // 定义一个有10个元素的管道
ch <- 1                      // 尝试向 管道中 写入第1个元素
// 成功写入！

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var ch = make(chan int, 10)    // 定义一个有 10 个元素的管道
close(ch)                      // 关闭管道
ch <- 11
// panic: send on closed channel

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var ch = make(<-chan int, 10)   // 定义一个有 10 个元素的管道
ch <- 11      // 编译错误 invalid operation: cannot send to receive-only channel c (variable of type <-chan int) 的的编译错误

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var ch chan int
close(ch)
// panic: close of nil channel

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ch := make(chan int, 2)
ch <- 1
ch <- 2
value, ok := <-ch
fmt.Println(value, ok) // 1 true
close(ch)
value, ok = <-ch
fmt.Println(value, ok) // 2 true
value, ok = <-ch
fmt.Println(value, ok) // 0 false
// 关闭channel，读取成功，知道通道耗尽，然后读取产生值的默认值

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ch := make(chan int, 2)
close(ch)
value, ok := <-ch
fmt.Println(value, ok) // 0 false

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ch := make(chan int, 2)
close(ch)
close(ch)
// panic: close of closed channel

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ch := make(<-chan int, 2)
close(ch)
// 编译错误: invalid operation: cannot close receive-only channel ch (variable of type <-chan int)