Basic string operations

1. Escape sequences

1.1. Basic rules

Escape sequences use a backslash, , rather than a forward slash.

Example:

name := "你可真是个\"小机灵鬼\""
//在这里直接使用"小机灵鬼"会报错，因为双引号是字符串的标志，所以需要使用转义符来表示引号：\"

1.2. Common escape sequences

Common Go escape sequences are shown below.

2. Formatted output

Println adds a newline. Print does not add a newline automatically.

2.1. Basic usage

Building output by joining many pieces can be cumbersome:

Use Printf for formatted output:

fmt.Printf("用户名：%s， 年龄：%d，地址：%s， 电话：%s\r\n",username, age, address, mobile )

2.2. Advantages and drawbacks

Advantage: readable and maintainable.

Drawback: formatting adds runtime overhead.

2.3. More formatting options

2.3.1. Default format and type

2.3.2. Integers

2.3.3. Characters

2.3.4. Strings

2.3.5. Floating-point values

3. Common string operations

3.1. Measuring string length

What “length” means depends on the data and the operation.

3.1.1. ASCII letters and digits

name := "hello world"
fmt.Println(len(name))

3.1.2. Strings containing Chinese characters

name := "hello 世界"
bytes := []byte(name)
fmt.Println(len(bytes))

3.2. Efficient string concatenation

3.2.1. Using +

username := "user" + "name"

3.2.2. Formatting at output time

fmt.Printf("用户名：%s， 年龄：%d，地址：%s， 电话：%s\r\n",username, age, address, mobile )

3.2.3. Using strings.Builder

This is useful for building a string from many pieces efficiently.

var builder strings.Builder
builder.WriteString("hello")
builder.WriteString("world")
result := builder.String()
fmt.Println(result)

3.3. Comparing strings

//等于
a := "hello"
b := "hello"
fmt.Println(a == b)

//不等于
a = "hello"
b = "world"
fmt.Println(a != b)

//大于
a = "hello"
b = "world"
fmt.Println(a > b)

//小于
a = "hello"
b = "world"
fmt.Println(a < b)

//大于等于
//小于等于
//……

3.4. Common functions in strings

3.4.1. Importing the package

import {
	"fmt"
	"strings"
}

3.4.2. Frequently used operations

(1) Check whether a string contains a substring

strings.Contains("hello world", "world")

(2) String length

name := "hello world"
len(name)

(3) Count occurrences of a substring

strings.Count("hello world", "l")

(4) Split a string

//以空格为分隔符进行分割
strings.Split("hello world", " ")

(5) Check a prefix or suffix

//前缀
strings.HasPrefix("hello world", "he")

//后缀
strings.HasSuffix("hello world", "ld")

(6) Find a substring’s position

//英文
strings.Index("hello world", "lo")

(7) Replace a substring

//把字符串里的所有l替换成a，替换前2个
//-1表示全部替换
strings.Replace("hello world", "l", "a", 2)

(8) Change letter case

//全转成小写
strings.ToLower("HELLO WORLD")

//全转成大写
strings.ToUpper("hello world")

(9) Trim specified characters

//去掉左右两边指定的字符，指定的字符可以是多个，比如空格，#，*等
strings.Trim("#hello #world#", "#")
//得到的结果是：hello #world

//左边的特殊字符
strings.TrimLeft("#hello #world#", "#")
//得到的结果是：hello #world#

//右边的特殊字符
strings.TrimRight("#hello #world#", "#")
//得到的结果是：#hello #world

For more functions, inspect the package source or documentation. Most IDEs let you jump from a function name to its definition.