Check if a character is a number in Golang

Saturday, December 19, 2020 • 2 minutes to read

Unicode is a computing standard for the consistent encoding symbols.

All the characters and symbols assigned a code.

For ex.

A U+0041
 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
 2407 is number rune
 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
 2407 is digit rune
 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.


Golang2020to-the-pointgolang

Golang String Replace

Convert Hexadecimal to Decimal and Decimal to Hexadecimal in Golang