Unicode.IsSpace

Whitespace characters often need to be handled in a different way than other characters. We need to test for spaces (and other whitespace chars).

With the unicode package, we can test for all whitespace without recalling the entire set ourselves. The unicode.IsSpace func is useful in many programs.

First example

Here we loop over the runes in a string. We use unicode.IsSpace on each rune to see if it is a space character. We also detect the ASCII code 32 (for space).

package main

import (
    "fmt"
    "unicode"
)

func main() {
    value := "\tHello, friends\n"

    // Loop over chars in string.
    for _, v := range value {
        // Test each character to see if it is whitespace.
        if unicode.IsSpace(v) {
            fmt.Println("Is space:", v)
            if v == 32 {
                fmt.Println("ASCII code for space")
            }
        }
    }
}
Is space: 9
Is space: 32
ASCII code for space
Is space: 10

TrimFunc, IsSpace

Consider a func like TrimFunc. The second argument required with TrimFunc is a func. We can pass unicode.IsSpace directly as the second argument.

package main

import (
    "fmt"
    "unicode"
    "strings"
)

func main() {
    value := "\n Hello, friends"

    // Use unicode.IsSpace as the func argument to TrimFunc.
    result := strings.TrimFunc(value, unicode.IsSpace)

    // Print before and after.
    fmt.Println("[" + value + "]")
    fmt.Println("[" + result + "]")
}
[
 Hello, friends]
[Hello, friends]

A review

The unicode module in Go has many methods that can be used to test ranges of characters. These funcs can lead to simpler, clearer and more standard Go code.