Check if a character is a number in Golang

Unicode is a computing standard for the consistent encoding symbols.

All the characters and symbols assigned a code.

For ex.

A U+0041
अ U+0905

All the Unicode is divided into various categories. Browse all the categories.

• Ll Lowercase Letters (a, b, µ, ɸ)
• Nl Letter Number (Ⅰ, ᛯ)
• Lo Other Letter (अ, ƻ)

Golang package unicode provides a wide range of validation methods on different set of Unicode.

IsNumber

IsNumber function validates the set of Unicode number characters, category N(Nd, Nl, No).

Syntax

func IsNumber(r rune) bool

package main

import (
    "fmt"
    "unicode"
)

func main() {
    str := "1b१Ⅰ¼"
    for _, char := range str {
        if unicode.IsNumber(char) {
            fmt.Println(string(char), char, "is number rune")
        } else {
            fmt.Println(string(char), char, "is not a number rune")
        }
    }
}

Output

1 49 is number rune
b 98 is not a number rune
१ 2407 is number rune
Ⅰ 8544 is number rune
¼ 188 is number rune

Try it

IsDigit

IsDigit function validates only the Nd Unicode category. It is a subset of IsNumber.

Syntax

func IsDigit(r rune) bool

package main

import (
    "fmt"
    "unicode"
)

func main() {
    str := "1b१Ⅰ¼"

    for _, char := range str {
        if unicode.IsDigit(char) {
            fmt.Println(string(char), char, "is digit rune")
        } else {
            fmt.Println(string(char), char, "is not a digit rune")
        }
    }
}

Output

1 49 is digit rune
b 98 is not a digit rune
१ 2407 is digit rune
Ⅰ 8544 is not a digit rune
¼ 188 is not a digit rune

Final Words

You can always use a validation on ASCII values. ASCII value of 0 is 30 and 9 is 39.
If >= 30 and <= 39.

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