In the previous post, I already introduced some methods to split a string in Golang. But the question is how we can assign the result after splitting the string to another variable. We are going to answer it today with some detailed examples.
Example 1: Split a string with strings.Split() function
func Split(s, sep string) []string: Split slices s into all substrings separated by sep and return a slice of the substrings between those separators. If s does not contain sep and sep is not empty, Split returns a slice of length 1 whose only element is s. If sep is empty, Split splits after each UTF-8 sequence. If both s and sep are empty, Split returns an empty slice.
We can see that the return value of this function is a string slice. We can create a slice and assign it as the return value of the Split() function:
package main
import (
"fmt"
"strings"
)
func main() {
var result []string
// split by space character
result = strings.Split("this is a split string example", " ")
fmt.Println(len(result))
fmt.Println("first element:", result[0])
fmt.Printf("type of result: %T\n", result)
}
Example 2: Split by whitespace or newline using Fields() function
func Fields(s string) []string: Fields splits the string s around each instance of one or more consecutive white space characters, as defined by unicode.IsSpace, returning a slice of substrings of s or an empty slice if s contains only white space.
The below code shows how to use Fields() function to split a string by whitespace or newline then assign the return value to a string slice
package main
import (
"fmt"
"strings"
)
func main() {
var result []string
// split by space character
result = strings.Fields(" \t \n this is \t split example \n \t ")
fmt.Println(len(result))
fmt.Println("first element:", result[0])
fmt.Printf("type of result: %T\n", result)
}
Output:
4
first element: this
type of result: []string
We can see that split functions usually return a string slice that contains all the elements after splitting. We can call the split functions and then assign the return value to a string array.
Example 3: Split an IP address by the SplitHostPort() function
For some special cases such as splitting an IP address, we can use the net.SplitHostPort() function to get the result:
func SplitHostPort(hostport string) (host, port string, err error): SplitHostPort splits a network address of the form "host:port", "host%zone:port", "[host]:port" or "[host%zone]:port" into host or host%zone and port. A literal IPv6 address in hostport must be enclosed in square brackets, as in "[::1]:80", "[::1%lo0]:80".
You can see this function returns three variables: the host, the port, and the error. In the example below, we will try to analyze an IP address by calling the SplitHostPort() function:
package main
import (
"fmt"
"net"
)
func main() {
host, port, err := net.SplitHostPort("127.0.0.1:8080")
if err == nil {
fmt.Println("The host:", host, " The port:", port, " Erorr:", err)
} else {
fmt.Println(err)
}
host2, port2, err2 := net.SplitHostPort("ACKSEWW8080")
if err2 == nil {
fmt.Println("The host:", host2, " The port:", port2, " Erorr:", err2)
} else {
fmt.Println(err2)
}
}Output:
The host: 127.0.0.1 The port: 8080 Erorr: <nil>
address ACKSEWW8080: missing port in address
Summary
As we can see, split functions typically return a string slice that includes every piece that was divided. We can use a string slice as the assigned return value. For some special split functions, the return values may different than the string slice. For example, the net.SplitHostPort() function which split an IP address return three values: the host, the port, and the error.
References
https://pkg.go.dev/net#SplitHostPort
https://pkg.go.dev/strings#Split
How to split a string and assign it to variables - Stack Overflow
