Go language foundation ----- 10 ----- string related operations (operation function, string conversion)

1 Common functions for string operations

1、Contains

func Contains(s, substr string) bool
 function ： character string s Include in substr, return bool value 

2、Join

func Join(a []string, sep string) string
 function ： String Links , hold slice a adopt sep link 　

3、Index

func Index(s, sep string) int
 function ： In string s Search for sep Where it is , Return position value , No return found -1

4、Repeat

func Repeat(s string, count int) string
 function ： repeat s character string count Time , Finally return the duplicate string 

5、Replace

func Replace(s, old, new string, n int) string
 function ： stay s In a string , hold old Replace the string with new character string ,n Indicates the number of replacements , Less than 0 Means replace all 

6、Split

func Split(s, sep string) []string
 function ： hold s String according to sep Division , return slice

7、Trim

func Trim(s string, cutset string) string
 function ： stay s The head and tail of the string are removed cutset Specified string 

8、Fields

func Fields(s string) []string
 function ： Remove s The space character of a string , And return according to the space division slice

2 Code practice

package main

import (
	"fmt"
	"strings"
)

func main(){
    
	// 1. Contains
	//"hellogo" Include in "hello",  Include return true,  Does not include return false
	fmt.Println(strings.Contains("hellogo", "hello"))
	fmt.Println(strings.Contains("hellogo", "abc"))

	// 2. Joins  Combine 
	s := []string{
    "abc", "hello", "mike", "go"}
	buf := strings.Join(s, "x")
	fmt.Println("buf = ", buf)

	// 3. Index,  Find the location of the substring 
	fmt.Println(strings.Index("abcdhello", "hello"))
	fmt.Println(strings.Index("abcdhello", "go")) // Returns... Without substring -1

	// 4.  How many repetitions , Repeat here 3 Time 
	buf = strings.Repeat("go", 3)
	fmt.Println("buf = ", buf) //"gogogo"

	// 5. Replace
	//  stay s In a string , hold old Replace the string with new character string ,n Indicates the number of replacements , Less than 0 Means replace all 
	fmt.Println(strings.Replace("oink oink oink", "k", "ky", 2))
	fmt.Println(strings.Replace("oink oink oink", "oink", "moo", -1))

	// 6. Split  Split... With the specified separator , Back to the slice 
	buf = "[email protected]@[email protected]"
	s2 := strings.Split(buf, "@")
	fmt.Println("s2 = ", s2)

	// 7. Trim Remove the characters at both ends 
	buf = strings.Trim(" are u ok? ", " ") // Remove the space at the end of the head 
	fmt.Printf("buf = #%s#\n", buf)
	fmt.Printf("[%q]\n", strings.Trim(" !!! Achtung !!! ", "! "))	//  Output : ["Achtung"]
	fmt.Printf("[%q]\n", strings.Trim(" !!! Achtung !!! ", " !"))	//  The same output : ["Achtung"]
																					//  explain Trim You can remove the space at the beginning and end 、! The content of .

	// 8.  Remove s The space character of a string , And return according to the space division slice
	s3 := strings.Fields(" are u ok? ")
	//fmt.Println("s3 = ", s3)
	for i, data := range s3 {
    
		fmt.Println(i, ", ", data)
	}
}

3 String conversion

package main

import (
	"fmt"
	"strconv"
)

func main(){
    

	// 1.  Convert to string and append to byte array 
	slice := make([]byte, 0, 1024)
	fmt.Println("slice = ", slice)
	slice = strconv.AppendBool(slice, true)
	// The second number is the number to be appended , The first 3 Specified 10 Add base mode 
	slice = strconv.AppendInt(slice, 1234, 10)
	slice = strconv.AppendQuote(slice, "abcgohello")
	fmt.Println("slice = ", string(slice)) // transformation string Then print 

	fmt.Println("=============================")

	// 2.  Other types are converted to strings 
	var str string
	str = strconv.FormatBool(false)
	fmt.Println("str = ", str)

	//'f'  Refers to the print format , In decimal form , -1 Refers to the number of decimal places ( Austerity mode ), 64 With float64 Handle 
	str = strconv.FormatFloat(3.14, 'f', -1, 64)
	fmt.Println("str = ", str)

	str = strconv.Itoa(6666)//  Integer to string , Commonly used 
	fmt.Println("str = ", str)

	fmt.Println("=============================")

	// 3.  String to other types 
	var flag bool
	var err error
	flag, err = strconv.ParseBool("true")
	if err == nil {
    
		fmt.Println("flag = ", flag)
	} else {
    
		fmt.Println("err = ", err)
	}

	a, _ := strconv.Atoi("567") //  Convert a string to an integer 
	fmt.Println("a = ", a)

}