Golang learning road-string commonly used system functions

Go language standard library documentation

1. The length of the statistical string (in bytes) len(str)

package main

import (
	"fmt"
)

func main(){
    
    
	//统计字符串的长度，按字节len(str)
	str := "Casey胡"
	fmt.Println("str len =",len(str))

}

operation result:

2. String traversal, processing Chinese

package main

import (
	"fmt"
)

func main(){
    
    
	//字符串遍历，同时处理有中文的问题 r := []rune(str)
	str := "Casey胡"
	r := []rune(str)
	for i := 0; i < len(r); i++{
    
    
		fmt.Printf("字符=%c\n",r[i])
	}

}

operation result:

3. Convert string to integer

package main

import (
	"fmt"
	"strconv"
)

func main(){
    
    
	n, err := strconv.Atoi("123")
	if err != nil{
    
    
		fmt.Println("转换错误....")
	}else{
    
    
		fmt.Println("转成的结果为：", n)
	}
}

operation result:

4. Integer to string

package main

import (
	"fmt"
	"strconv"
)

func main(){
    
    
   str := strconv.Itoa(123456)
   fmt.Printf("str = %v,str = %T",str,str)
}

operation result:

5. Convert string to []byte

package main

import (
	"fmt"
	//"strconv"
)

func main(){
    
    
   var bytes = []byte("hello Go!")
   fmt.Printf("bytes = %v",bytes)
}

operation result:

6, [] byte string skewer

package main

import (
	"fmt"
	//"strconv"
)

func main(){
    
    
   str := string([]byte{
    
    97,98,99})
   fmt.Printf("str = %v\n",str)
}

operation result:

7, decimal to 2, 8, hexadecimal

package main

import (
	"fmt"
	"strconv"
)

func main(){
    
    
   
	str := strconv.FormatInt(123,2)
	fmt.Printf("123对应的2进制是=%v\n",str)
	str = strconv.FormatInt(123,8)
	fmt.Printf("123对应的8进制是=%v\n",str)
	str = strconv.FormatInt(123,16)
	fmt.Printf("123对应的16进制是=%v\n",str)

}

operation result:

8. Find whether the substring is in the specified string

package main

import (
	"fmt"
	//"strconv"
	"strings"
)

func main(){
    
    
   
 //字符串"Casey"中是否含有子串"sey"，是返回true，否返回false
  b := strings.Contains("Casey","sey")
  fmt.Printf("b = %v\n",b)

}

operation result:

9. Count how many specified substrings of a string

package main

import (
	"fmt"
	//"strconv"
	"strings"
)

func main(){
    
    
   
 //字符串"Casey"中是否含有子串"sey"，是返回true，否返回false
  num := strings.Count("CaseyCasey","sey")
  fmt.Printf("num = %v\n",num)

}

operation result:

10. Case-insensitive string comparison

package main

import (
	"fmt"
	//"strconv"
	"strings"
)

func main(){
    
    
   
 b := strings.EqualFold("abc","aBc")//true
 fmt.Printf("b = %v\n",b)
 //==是区分字母大小写的
 fmt.Println("结果 =","abc" == "aBc")//false

}

operation result:

11. Return the position of the first occurrence of the substring in the string

package main

import (
	"fmt"
	//"strconv"
	"strings"
)

func main(){
    
    
   
//返回子串在字符串中第一次出现的index值，如果没有则返回-1
index := strings.Index("CaseyCasey","sey")
fmt.Printf("index = %v\n",index)

}

operation result:

12. Return the position of the last occurrence of the substring in the string

package main

import (
	"fmt"
	//"strconv"
	"strings"
)

func main(){
    
    
   
//返回子串在字符串中最后一次出现的index值，如果没有则返回-1
index := strings.LastIndex("CaseyCasey","sey")
fmt.Printf("index = %v\n",index)

}

operation result:

13. Replace the specified substring with another substring

package main

import (
	"fmt"
	//"strconv"
	"strings"
)

func main(){
    
    
   
//将指定子串替换成另一个子串
str := "go go Casey"
//-1代表全部替换，若希望替换1个，则该位置的值改为1即可
str1 := strings.Replace(str,"go","胡",-1)
fmt.Println("str1 =",str1)

}

operation result:

14. Split the string according to the specified characters

package main

import (
	"fmt"
	//"strconv"
	"strings"
)

func main(){
    
    
	
	//按照指定的某个字符，为分割符，讲一个字符拆分为字符串数组
	str := "go/go/Casey"
	strArr := strings.Split(str,"/")

	for i := 0; i < len(strArr); i++{
    
    
		fmt.Printf("strArr[%v] = %v\n",i,strArr[i])
	}
	fmt.Printf("strArr = %v\n",strArr)


}

operation result:

15. Convert the letters of the string to case

package main

import (
	"fmt"
	"strings"
)

func main(){
    
    
	
	str := "Casey"
	str1 := strings.ToLower(str)
	str2 := strings.ToUpper(str)
	fmt.Printf("str = %v,str1 = %v,str2 = %v\n", str, str1, str2)

}

operation result:

17. Remove the specified characters on the left and right sides of the string

package main

import (
	"fmt"
	"strings"
)

func main(){
    
    
	
	//将字符串左右两边的空格去掉
	str := strings.TrimSpace("hello go go")
	fmt.Printf("str = %v\n",str)

	//将字符串左右两边指定的字符去掉
	str = strings.Trim("! hello !!","!")
	fmt.Printf("str = %v\n",str)

	//将字符串左边指定的字符去掉
	str = strings.TrimLeft("! hello !!","!")
	fmt.Printf("str = %v\n",str)

	//将字符串右边指定的字符去掉
	str = strings.TrimRight("! hello !!","!")
	fmt.Printf("str = %v\n",str)
}

operation result:

18. Determine whether the string starts with the specified string

package main

import (
	"fmt"
	"strings"
)

func main(){
    
    
	
	//判断字符串是否以指定字符串开头
	b := strings.HasPrefix("Casey go go","Casey")
	fmt.Printf("b = %v\n",b)
}

operation result:

19. Determine whether the string ends with the specified string

package main

import (
	"fmt"
	"strings"
)

func main(){
    
    
	
	//判断字符串是否以指定字符串结束
	b := strings.HasSuffix("Casey go","go")
	fmt.Printf("b = %v\n",b)
}

operation result: