C# | Char.IsNumber() Method

In C#, Char.IsNumber() is a System.Char struct method which is used to check whether a Unicode character can be categorized as a number or not. Valid numbers will be the members of the UnicodeCategory.DecimalDigitNumber, UnicodeCategory.LetterNumber, or UnicodeCategory.OtherNumber category.

This method can be overloaded by passing different type and number of arguments to it.

1. Char.IsNumber(Char) Method
2. Char.IsNumber(String, Int32) Method

Note: The only difference between Char.IsDigit() and Char.IsNumber() method is that IsDigit() method will only check whether a Char is a radix-10 digit or not. While IsNumber() method will check whether a char is a decimal digit, numbers include characters, fractions, subscripts, superscripts, Roman numerals, currency numerators, and encircled numbers or not.

Char.IsNumber(Char) Method

This method is used to check whether the specified Unicode character matches number or not. If it matches then it returns True otherwise return False.

Syntax:

public static bool IsNumber(char ch);

Parameter:

ch: It is required Unicode character of System.char type which is to be checked.

Return Type: The method returns True, if it successfully matches any number, otherwise returns False. The return type of this method is System.Boolean.

Example:

// C# program to illustrate the
// Char.IsNumber(Char) Method
using System;

class GFG {

    // Main Method
    static public void Main()
    {

        // Declaration of data type
        bool result;

        // checking if 5 is a
        // number or not
        char ch1 = '5';
        result = Char.IsNumber(ch1);
        Console.WriteLine(result);

        // checking if 'c' is a
        // number or not
        char ch2 = 'c';
        result = Char.IsNumber(ch2);
        Console.WriteLine(result);
    }
}

Output:

True
False

Char.IsNumber(String, Int32) Method

This method is used to check whether the specified string at specified position matches with any number or not. If it matches then it returns True otherwise returns False.

Syntax:

public static bool IsNumber(string str, int index);

Parameters:

Str: It is the required string of System.String type which is to be evaluate.
index: It is the position of character in string to be compared and type of this parameter is System.Int32.

Return Type: The method returns True if it successfully matches any number at the specified index in the specified string, otherwise returns False. The return type of this method is System.Boolean.

Exceptions:

• If the value of str is null then this method will give ArgumentNullException.
• If the index is less than zero or greater than the last position in str then this method will give ArgumentOutOfRangeException.

Example:

// C# program to illustrate the
// Char.IsNumber(String, Int32) Method
using System;

class GFG {

    // Main Method
    static public void Main()
    {

        // Declaration of data type
        bool result;

        // checking for number in a
        // string at a desired position
        string str1 = "GeeksforGeeks";
        result = Char.IsNumber(str1, 2);
        Console.WriteLine(result);

        // checking for number in a
        // string at a desired position
        string str2 = "geeks5forgeeks";
        result = Char.IsNumber(str2, 5);
        Console.WriteLine(result);
    }
}

Output:

False
True

Reference: https://docs.microsoft.com/en-us/dotnet/api/system.char.IsNumber?view=netframework-4.7.2