✨ new & make

Author: tmpbook

type/README.md

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+> new 的作用是初始化一个指向类型的指针(*T)，make 的作用是为 slice，map 或 chan 初始化并返回引用(T)

type/make/main.go

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+package main
+
+import "fmt"
+
+/**
+ *  func make(Type, size IntegerType) Type
+ *  Only support slice, map, chan type
+ */
+
+func main() {
+	a := make([]int, 5)
+	printSlice("a", a)
+	b := make([]int, 0, 5)
+	printSlice("b", b)
+	c := b[:2]
+	printSlice("c", c)
+	d := c[2:5]
+	printSlice("d", d)
+}
+
+func printSlice(s string, x []int) {
+	fmt.Printf("%s len=%d cap=%d %v\n",
+		s, len(x), cap(x), x)
+}

type/new/main.go

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+package main
+
+import (
+	"fmt"
+)
+
+// func new(Type) *Type
+
+// 和 build-in 方法：new(int) 一样
+func newInt() *int {
+	var i int
+	return &i
+}
+func newString() *string {
+	var i string
+	return &i
+}
+
+func main() {
+	myNewInt := newInt()
+	fmt.Println(*myNewInt)
+
+	myNewString := newString()
+	fmt.Println(*myNewString)
+}