add

basic.go

 package main
 
-import "fmt"
+import (
+	"fmt"
+	"math"
+	"math/cmplx"
+)
 
 /*此处不能使用 := 来定义变量
  go 语言都中包内变量，go 没有全局变量
@@ -42,7 +46,56 @@ func variableShorter()  {
 	 x ,b  ,c,e,f  := 3.23,4,"abdad",true, 4.54
 	fmt.Println(x,b,f+1, c,e)
 }
+func euler()  {
+	c:=3 +4i
+	fmt.Println(cmplx.Abs(c))
+}
+/*强制转换*/
+func triangle()  {
+	a ,b  :=3,5
+	var c int
+	c = int(math.Sqrt(float64(a*a + b*b)))
+	fmt.Println(c)
+}
+/*常量*/
+func consts()  {
+	/*const filename="abc.txt"
+	const a, b  = 3, 4 */
+	/* 集中写常量*/
+	const(
+	  filename ="abc.txt"
+	  a, b  = 3, 4
+	)
+	var c int
+	c = int(math.Sqrt(a*a + b*b))
+	fmt.Println(filename,c )
+}
+/*枚举*/
+func enums()  {
+	/*常量定义必须给赋值*/
+	const(
+		cpp=iota // 自动填充递长
+		java
+		python
+		golang
+		javasscipt
+		 _      // 下划线跳过自动填充值
+		php
+	)
+	const x int =0
+	fmt.Println(x, cpp,python,golang,javasscipt,java,php)
 
+	/*设置自增表达式*/
+	const(
+		b = 1 <<(10*iota)
+		kb
+		mb
+		gb
+		tb
+		pb
+	)
+	fmt.Println(b,kb,mb,gb,tb,pb)
+}
 
 func main() {
 	variableZeroValue()
@@ -50,5 +103,8 @@ func main() {
 	variableTypeDeduction()
 	variableShorter()
 	fmt.Println(x1,x2,x3)
-
+	euler()
+	triangle()
+	consts()
+	enums()
 }

go.mod

-module "learngo"
\ No newline at end of file
+module learngo
+
+go 1.15