7 days to learn Go, Go structure + Go range to learn

Write before studying

In the previous blog we learned Go 数组,It requires all elements to be of the same data type,If you want to store different types of data,Knowledge of structures is required.

结构体的定义：Store collections of data of the same or different types.

有 C 相关经验,Structures are relatively easy to understand,语法格式如下所示：

type struct_variable_type struct {
    
   member definition
   member definition
   ...
   member definition
}

The keywords in the above syntax format are struct 和 type,struct_variable_type 是结构体名称,例如我们声明一个【人】的结构体,有姓名,有年龄,有性别.

package main

import "fmt"

// 声明结构体
type People struct {
    
	name string
	age  int
	sex  int
}

func main() {
    
	//使用结构体
	people := People{
    
		"橡皮擦",
		18,
		0}
	fmt.Println(people)
}

Pay attention to the syntax when writing,The code for using the structure is recommended to be placed on one line,Or a closing brace immediately following the last element.

Using structs can also carry element names,That is, the following writing.

//使用结构体
people := People{
    name: "橡皮擦", age: 18, sex: 0}
fmt.Println(people)

访问结构体成员
使用 结构体.成员名 即可,Of course, you can also use this method to assign values.

//使用结构体
var people1 People
// var people2 People

people1.name = "橡皮擦"
people1.age = 18
people1.sex = 1

fmt.Println(people1)

Go Range

作为一个 Python 程序员,关键字 range 是非常熟悉的,在 Go 中 range 关键字可以用于 for 循环,For arrays it returns the index and value of the element,Returns key-value pairs in the subsequently learned collection.

range The syntax format for arrays is as follows：

for i,value := range a_array{
    
	// TODO
}

Combining grammatical formats,Write the following code：

package main

import "fmt"

var a_array = []int{
    1, 2, 3, 4, 5, 6, 7, 8}

func main() {
    
	for i, value := range a_array {
    
		fmt.Printf("索引：%d,值：%d\n", i, value)
	}
}

Running the code outputs the following information：

索引：0,值：1
索引：1,值：2
索引：2,值：3
索引：3,值：4
索引：4,值：5
索引：5,值：6
索引：6,值：7
索引：7,值：8

如果将 range 作用于字符串,Each character can be iteratively output.

package main

import (
	"fmt"
)

func main() {
    
	var str string = "xiangpica"
	for k, v := range str {
    
		fmt.Println(k, string(v))
	}
}

上述 str The content is in pure English,k value every time+1.

0 x
1 i
2 a
3 n
4 g
5 p
6 i
7 c
8 a

如果 str 中包含中文,k value every time +3,代码如下：

func main() {
    
	var str string = "橡皮擦"
	for k, v := range str {
    
		fmt.Println(k, string(v))
	}
}

输出结果如下：

0 橡
3 皮
6 擦

If it is a mix of Chinese and English,The results that appear will be more interesting.

0 x
1 i
2 a
3 n
4 g
5 橡
8 p
9 i
10 皮
13 c
14 a
15 擦

There is actually a conclusion here,range Iteration yes Unicode,而不是字节,返回值是 UTF-8 编码第 1 个字节的索引,So the index values ​​may not be consecutive.

在编写代码的时候,如果不需要索引,Only elements are kept,Deprecated placeholders can be used,代码如下：

var str string = "xiang橡pi皮ca擦"
for _, v := range str {
    
	fmt.Println(string(v))
}