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:

// 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 GetNumericValue() 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}' does't contain control "+ 
                                      "character at index {1}", s, i); 
    } 
} 

Output:

String '1234' does't contain control character at index 3
String 'Tsunami' 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.

Example 2: For ArgumentNullException

// 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 GetNumericValue() 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}' does'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

// 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 GetNumericValue() 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}' does'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_

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