1 package main
 2 import (
 3   "strconv"
 4   "fmt"
 5   "strings"
 6 )
 7 func main() {
 8 
 9     str := "Hello World test!"
10     result := strings.Replace(str, "World", "golang", 1)
11     fmt.Println(result)
12 
13     count := strings.Count(str, "o")
14     fmt.Println(count)
15 
16     result = strings.Repeat(str, 3)
17     fmt.Println(result)    
18 
19     result = strings.ToUpper(str)
20     fmt.Println(result)    
21 
22     result = strings.ToLower(str)
23     fmt.Println(result)    
24 
25     result = strings.TrimSpace(str)
26     fmt.Println("trimSpace:" ,result)
27 
28     result = strings.Trim(str, " \n\r")
29     fmt.Println("trim:" ,result)
30 
31     result =  strings.TrimLeft(str, " \n\r")
32     fmt.Println("trimleft:" ,result)
33 
34     result =  strings.TrimRight(str, " \n\r")
35     fmt.Println("trimright:" ,result)
36 
37     splitResult := strings.Fields(str)
38     for i := 0; i < len(splitResult); i++ {
39         fmt.Println(splitResult[i])
40     }
41     str2 := strings.Join(splitResult, "l")
42     fmt.Println("join:", str2)
43 
44     str2 = strconv.Itoa(1000)
45     fmt.Println("itoa:", str2)
46 
47     number, err := strconv.Atoi(str2)
48     if err != nil {
49         fmt.Println("can not convert to int,", err)
50         return
51     }
52     fmt.Println("number:", number)
53 }