C# | Char.IsControl(String, Int32) Method

This method is used to indicates whether the character at the specified position in a specified string is categorized as a control character.

Syntax:

public static bool IsControl (string s, int index);

Parameters:

s: It is the String. index: It is the character position in s.

Return Value: This method returns true if the character at position index in s is a control character otherwise it returns, false. 

Exceptions: 

• ArgumentNullException: If the s is null.
• ArgumentOutOfRangeException: If the index is less than zero or greater than the last position in s.

Note: Control characters are formatting and other non-printing characters, such as ACK, BEL, CR, FF, LF, and VT. 

Below programs illustrate the use of Char.IsControl(String, Int32) Method: 

Example 1:

csharp

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

class GFG {

    // Main Method
    public static void Main()
    {

        try {

            // calling check() Method
            check("1234", 3);
            check("Tsunami", 3);
            check("psyc0lo", 4);
            check("a" + Environment.NewLine + "b", 1);
        }

        catch (ArgumentNullException e) {

            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }

        catch (ArgumentOutOfRangeException e) {

            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }

    // Defining check() method
    public static void check(string s, int i)
    {

        // checking condition
        // using IsControl() Method
        bool val = Char.IsControl(s, i);

        // checking
        if (val)
            Console.WriteLine("Control character \\U{0} "+
                                 "found in position {1}.",
                 Convert.ToInt32(s[i]).ToString("X4"), i);

        else
            Console.WriteLine("String '{0}' doesn't contain control "+
                                      "character at index {1}", s, i);
    }
}

Example 2: For ArgumentNullException

csharp

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

class GFG {

    // Main Method
    public static void Main()
    {
        try {

            // calling check() Method
            check("1234", 3);
            check("psyc0lo", 4);
            check("a" + Environment.NewLine + "b", 1);
            Console.WriteLine("");
            Console.WriteLine("s is null");
            check(null, 4);
        }
        catch (ArgumentNullException e) {

            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
        catch (ArgumentOutOfRangeException e) {

            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }

    // Defining check() method
    public static void check(string s, int i)
    {
        // checking condition
        // using IsControl() Method
        bool val = Char.IsControl(s, i);

        // checking
        if (val)
            Console.WriteLine("Control character \\U{0} found"+
                                           " in position {1}.",
                       Convert.ToInt32(s[i]).ToString("X4"), i);
        else
            Console.WriteLine("String '{0}' doesn't contain "+
                     "control character at index {1}", s, i);
    }
}

Output:

String '1234' does't contain control character at index 3
String 'psyc0lo' does't contain control character at index 4
Control character \U000A found in position 1.

s is null
Exception Thrown: System.ArgumentNullException

Example 3: For ArgumentOutOfRangeException 

csharp

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

class GFG {

    // Main Method
    public static void Main()
    {
        try {

            // calling check() Method
            check("1234", 3);
            check("psyc0lo", 4);
            check("a" + Environment.NewLine + "b", 1);

            Console.WriteLine("");
            Console.WriteLine("index is less than zero");

            check("null", -1);
        }
        catch (ArgumentNullException e) {

            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
        catch (ArgumentOutOfRangeException e) {

            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }

    // Defining check() method
    public static void check(string s, int i)
    {
        // checking condition
        // using IsControl() Method
        bool val = Char.IsControl(s, i);

        // checking
        if (val)
            Console.WriteLine("Control character \\U{0} found "+
                                              "in position {1}.",
                        Convert.ToInt32(s[i]).ToString("X4"), i);
        else
            Console.WriteLine("String '{0}' doesn't contain control"+
                                   " character at index {1}", s, i);
    }
}

Output:

String '1234' does't contain control character at index 3
String 'psyc0lo' does't contain control character at index 4
Control character \U000A found in position 1.

index is less than zero
Exception Thrown: System.ArgumentOutOfRangeException

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.char.iscontrol?view=netframework-4.7.2#System_Char_IsControl_System_String_System_Int32_