golang学习之指针、内存分配

 func pointer_test() {
     //空指针，输出为nil
     var p *int
     fmt.Printf("p: %v\n", p)
     //指向局部变量，变量值初始为0
     var i int
     p = &i
     fmt.Printf("p: %v,%v\n", p, *p)
     //通过指针修改变量数值
     *p =
     fmt.Printf("p: %v,%v\n", p, *p)
     //数组的初始化及输出
     m := []int{, , }
     fmt.Printf("m:%v--%v,%v,%v\n", m, m[], m[], m[])
     //指针数组的初始化及输出
     //j, k, l := 3, 4, 5
     //x := [3]*int{&j, &k, &l}
     x := []*int{&m[], &m[], &m[]}
     fmt.Printf("x:%v,%v,%v\n", x[], x[], x[])
     fmt.Printf("*x:%v,%v,%v\n", *x[], *x[], *x[])

     var n []*int
     n = x
     fmt.Printf("n:%v,%v,%v\n", n[], n[], n[])
     //指向数组的指针，也即二级指针的使用
     y := []*[]*int{&x}
     fmt.Printf("y:%v,%v\n", y, y[])
     fmt.Printf("*y[0]:%v\n", *y[])
     fmt.Printf("*y[][]:%v,%v,%v\n", *y[][], *y[][], *y[][])
     /*
         *X            ->    v
         [3]X        ->    [v0][v1][v2]
         []X            ->    [v0]...[vi]
         [3]*X        ->    [p0][p1][p2]
                           |   |   |
                           j   k   l
         []*[3]*X    ->    [n0]...[ni]
                           | ... |
                          [p0]->j
                          [p1]->k
                          [p2]->l
     */
 }

 type Student struct {
     name  string
     id    int
     score uint
 }

 func memery_test() {
     //new分配出来的数据是指针形式
     p := new(Student)
     p.name = "China"
     p.id =
     p.score =
     fmt.Println(*p)
     //var定义的变量是数值形式
     var st Student
     st.name = "Chinese"
     st.id =
     st.score =
     fmt.Println(st)
     //make分配slice、map和channel的空间，并且返回的不是指针
     var ptr *[]Student
     fmt.Println(ptr)     //ptr == nil
     ptr = new([]Student) //指向一个空的slice
     fmt.Println(ptr)
     *ptr = make([]Student, , )
     fmt.Println(ptr)
     stu := []Student{{"China", , }, {"Chinese", , }, {"Chince", , }}
     fmt.Println(stu)
 }