[ 常見問題 ] Substring: How to Split a String

 Source From Here

Preface
In the example below we are looking at how to take the first x number of characters from the start of a string. If we know a character we want to separate on, like a space, we can use strings.Split() instead. But for this we’re looking to get the first 6 characters as a new string.

HowTo
To do this we first convert it into a rune, allowing for better support in different languages and allowing us to use it like an array. Then we pick the first characters using [0:6] and converting it back to a string.

Split Based on Position:

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1. package main  
2.   
3. import (  
4.     "fmt"  
5. )  
6.   
7. func main() {  
8.   
9.     myString := "Hello! This is a golangcode.com test ;)"  
10.   
11.     // Step 1: Convert it to a rune  
12.     a := []rune(myString)  
13.   
14.     // Step 2: Grab the num of chars you need  
15.     myShortString := string(a[0:6])  
16.   
17.     fmt.Println(myShortString)  
18. }  

Output:

Hello!

Split Based on Character:
The alternative way, using the strings package would be:

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1. package main  
2.   
3. import (  
4.     "fmt"  
5.     "strings"  
6. )  
7.   
8. func main() {  
9.   
10.     myString := "Hello! This is a golangcode.com test ;)"  
11.   
12.     strParts := strings.Split(myString, "!")  
13.   
14.     fmt.Println(strParts[0])  
15. }  

Output:

Hello

Supplement
* The Go Blog - Strings, bytes, runes and characters in Go

The Go language defines the word rune as an alias for the type int32, so programs can be clear when an integer value represents a code point. Moreover, what you might think of as a character constant is called a rune constant in Go...