Golang

for loop

don't need (), but always need{}

• classic c like

for initvaule = value; condition < condition-value; endcondition{

}

• while like

for condition {

}

• ranged for

for index, value := range os.Args[1:]{

}

if/else loop

• can have init part(init part can visiable in if or else )

if init := value; condition-expression{

}else{

}

switch

• nomal syntax

switch expression {
case condition:

}

• no expression, just like switch true

switch {
case condition:

}

stacking defers

Deferred function calls are pushed onto a stack. When a function returns, its deferred calls are executed in last-in-first-out order.

package main

import "fmt"

func main() {
	fmt.Println("counting")

	for i := 0; i < 10; i++ {
		defer fmt.Println(i)
	}

	fmt.Println("done")
}

interface value & type assert

1. an interface variable holds a tuple of a value and a type (value, type)
2. x.(T) :x is a interface and T is a tpye in interface

data types

• basic types numbers, strings, booleans

• aggregate tpyes arrays, structs

• reference types pointers, slices, maps, functions, channels

printf format

• %b, %d, %o, %x(%X) 十进制， 八进制， 十六进制(x大小写表明字母的大小写)

• %c, %q 字符，带引号的字符

• %g, %f, %e 浮点数，%e是exponent表示

• %T 值的类型

• %t boolean value: true or false

go goroutine 和 thread的区别

1. thread 的栈一般为2mb (固定的大小); goroutine 的栈一般为2kb, 可以动态改变
2. thread 是系统的schedule统一调度、分配，切换thread需要full context switch; goroutine拥有自己的schedule, it only concerns the goroutine of one go program(go's schedule use a parameter GOMAXPROCS to determine how many OS threads be executing go code simulately; its default value is the cpus of the machine)
3. goroutine has no identity (like thread-id of threads, which thread-local storage based on it)