发表于 2024-01-16

interface类型转换

value    interface{}
op,ok:= value.(要转换的类型)
value.(type)//获取类型

defer

defer 语句会将函数推迟到外层函数返回之后执行。

推迟调用的函数其参数会立即求值，但直到外层函数返回前该函数都不会被调用。

数组类型 [n]T 表示拥有 n 个 T 类型的值的数组。

var a [10]int

primes := [6]int{2, 3, 5, 7, 11, 13}

var s []int = primes[1:4]

range

//当使用 `for` 循环遍历切片时，每次迭代都会返回两个值。第一个值为当前元素的下标，第二个值为该下标所对应元素的一份副本。
var pow = []int{1, 2, 4, 8, 16, 32, 64, 128}

func main() {
	for i, v := range pow {
		fmt.Printf("2**%d = %d\n", i, v)
	}
}

映射
make 函数会返回给定类型的映射，并将其初始化备用。

var m map[string]Vertex
m = make(map[string]Vertex)
elem, ok := m[key]
delete(m, key)
elem = m[key]

哈希表

Insert or update an element in map m:

m[key] = elem

Retrieve an element:

elem = m[key]

Delete an element:

delete(m, key)

Test that a key is present with a two-value assignment:

elem, ok = m[key]

If key is in m, ok is true. If not, ok is false.

If key is not in the map, then elem is the zero value for the map’s element type.

Note: If elem or ok have not yet been declared you could use a short declaration form:

elem, ok := m[key]

go panic: assignment to entry in nil map（没有初始化）

并发

var wg sync.WaitGroup
wg.add(1)
go func(){
    wg.Done()
}()
wg.Wait()

var wg sync.WaitGroup
for i:=0;i<5;i++{
    wg.Add(1)
    go func(x int){
        sendRPC(x)
        wg.Done()
    }(i);
    wg.Wait()
}


var wg sync.WaitGroup
for i:=0;i<5;i++{
    wg.Add(1)
    go func(){
        sendRPC
        ()
        wg.Done()
    }();
    wg.Wait()
}