package mainimport "fmt"// 定义一个结构体,类似于类
// 将Cat 的各个字段/属性,放入到结构体中
type Cat struct {Name stringAge uintColor stringHobby string
}
func main(){// 声明一个Cat 变量,也就是实例var a1 Cata1.Name = "小花"a1.Age = 2a1.Color = "black"a1.Hobby = "老鼠"fmt.Println(a1)fmt.Printf("name=%s\n",a1.Name)fmt.Printf("age=%d\n",a1.Age)fmt.Printf("color=%s\n",a1.Color)fmt.Printf("hobby=%s\n",a1.Hobby)
}

package mainimport "fmt"// 如果结构体里的字段是引用类型的: slice map channel;
// 在使用前需要make分配内存才能使用;
type Person struct {Name stringAge intHobby [3]stringptr *stringslice []intParents map[string]string
}
type Cat struct {Name stringAge int
}
func main(){var a1 Personfmt.Println(a1) //{0 [] nil [] map[]}if a1.ptr == nil {fmt.Println("ptr is nil")}if a1.slice == nil {fmt.Println("slice is nil")}if a1.Parents == nil {fmt.Println("parents is nil")}// 结构体字段是引用类型的话,使用前需要makea1.slice = make([]int,10)a1.slice[0] = 1a1.slice[1] = 2a1.slice[2] = 3a1.Parents = make(map[string]string)a1.Parents["name"] = "aaaa"a1.Parents["friendly"] = "father"fmt.Println(a1) // { 0 [  ] <nil> [1 2 3 0 0 0 0 0 0 0] map[friendly:father name:aaaa]}// 不同结构体变量间互不影响var c1 Catvar c2 Catc1.Name = "c1"c2.Name = "c2"c1.Age = 1c2.Age = 2fmt.Println(c1,c2) //{c1 1} {c2 2}
}

package mainimport "fmt"type Cat struct {Name stringAge int
}
func main(){// 方式1: 先声明,再赋值var c1 Catc1.Name = "c1"c1.Age = 1fmt.Println(c1) //{c1 1}// 方式2: 字面量方式var c2 Cat = Cat{"c2",2}fmt.Println(c2) //{c2 2}// 方式3: 类型推导方式c3 := Cat{"c3",3}fmt.Println(c3) //{c3 3}// 方式4: new 方式var c4 *Cat = new(Cat)c4.Name = "c4"c4.Age = 4fmt.Println(*c4)// 方式5: &{} 方式var c5 *Cat = &Cat{}c5.Name = "c5"c5.Age = 5fmt.Println(*c5)// 方式4,方式5 返回的都是结构体的指针类型
}

package mainimport ("encoding/json""fmt"
)type Person struct {Name stringAge intHobby string
}
type Student struct {Name stringAge intHobby string
}
type Cat struct {Name string `json:"name"`Age int `json:"age"`
}
func main(){var p1 Personp1.Name = "p1"p1.Age = 22p1.Hobby = "run"// 结构体变量的地址fmt.Printf("p1 address: %p\n",&p1)fmt.Printf("p1.Name address: %p\n",&p1.Name) // 0xc0000562d0fmt.Printf("p1.Age address: %p\n",&p1.Age) //   0xc0000562e0 , 一个string 是16 字节fmt.Printf("p1.Hobby address: %p\n",&p1.Hobby)//0xc0000562e8 , 一个int 在64 位系统中为8字节// 类型之间强转var s1 Students1 = Student(p1)fmt.Println(s1)fmt.Printf("s1 type is %T\n",s1) // Student// struct tagvar c1 Catc1.Name = "小花"c1.Age = 12jsonStr,err := json.Marshal(c1)if err != nil {fmt.Println(err)}// 输出的是结构体中tag 定义的名称fmt.Println(string(jsonStr)) // {"name":"小花","age":12}
}