golang comma ok pattern integration demo

/*
@Time : 2019-02-23 11:49 
@Author : Tenlu
@File : ok
@Software: GoLand
*/
package main
import "fmt"
// Comma ok modefunc main() {
    useMap()
    useChan()
    userType()
        useType2()
}
//1. Detect whether the map contains the specified keyfunc useMap() {
    company := map[string]string{"polly": "tencent", "robin": "baidu", "jack": "alibaba", "tenlu": "itech8"}
    if _, ok := company["toms"]; !ok {
        ("key toms is not exists")
    }
    for ck, cv := range company {
        (ck + "->" + cv)
    }
}
// 2. Check whether chan is closedfunc useChan() {
    ch := make(chan int, 10)
    for i := 1; i <= 5; i++ {
        ch <- i
    }
    close(ch) // The chan assignment ends, the channel must be closed    elem := <-ch
    (elem) // 1 // FIFO queue, the chan sent first must be received first    for cc := range ch {
        (cc)
    }
        // ch <-8 // At this time, sending data to ch chan, an error will be reported because the channel has been closed. panic:send on closed channel    elem2 := &lt;-ch
    elem3 := &lt;-ch
    ("elem2:%d\n", elem2) // 0, because the channel has been closed    ("elem3:%d\n", elem3) // 0
    if _, isClosed := &lt;-ch; !isClosed {
        ("channel closed")
    }
    // Go does not have a while loop, here is similar to while(true) in other languages    for {
        i, ok := &lt;-ch
        if !ok {
            ("channel closed!")
            break
        }
        (i)
    }
}
// 3. Detect whether the interface type is implementedtype I interface {
    // There is an interface for method I    Get() Int
}
type Int int
// Int type implements I interfacefunc (i Int) Get() Int {
    return i
}
func userType() {
    var myint Int = 5
    var inter I = myint // Assign variables to interface    val, ok := inter.(Int)
    ("%v, %v\n", val, ok) // The output is: 5, true}
func useType2()  {
   // The null value of chan type is nil, and it needs to be used with make after declaration.   var ch=make(chan interface{},10)
   ch&lt;-10
   ch&lt;-"jack"
   ch&lt;-map[string]interface{}{"name":"jack","age":11}
   close(ch) // If you do not close the channel, an error will be reported during traversal.   ("%v\n",&lt;- ch)
   for c:=range ch {
      ("for:%v\n",c)
      ("type:%T\n", c)
      if newValue,ok:=c.(map[string]interface{});ok{
         ("type:%s\n",(c)) // Get variable type         // map[string]interface {}
         if _,ok:=newValue["name"];ok{
            for k,v:=range newValue {
               ("%v-&gt;%v,\n",k,v)
            }
         }
      }
   }
   ("%v\n",&lt;- ch) // nil
}
func useType2()  {
   // The null value of chan type is nil, and it needs to be used with make after declaration.   var ch=make(chan interface{},10)
   ch&lt;-10
   ch&lt;-"jack"
   ch&lt;-map[string]interface{}{"name":"jack","age":11}
   close(ch) // If you do not close the channel, an error will be reported during traversal.   ("%v\n",&lt;- ch)
   for c:=range ch {
      ("for:%v\n",c)
      ("type:%T\n", c)
      if newValue,ok:=c.(map[string]interface{});ok{
         ("type:%s\n",(c)) // Get variable type         // map[string]interface {}
         if _,ok:=newValue["name"];ok{
            for k,v:=range newValue {
               ("%v-&gt;%v,\n",k,v)
            }
         }
      }
   }
   ("%v\n",&lt;- ch) // nil
}