C# String Contains()

using System;  
namespace CsharpString {  
  class Test {
    public static void Main(string [] args) {
   
      string str = "I love ice cream";  

      // check if str contains "ice cream"
      bool check = str.Contains("ice cream");

      Console.WriteLine(check);   

      Console.ReadLine();    
    }
  }
}

// Output: True

Contains() Syntax

The syntax of the string Contains() method is:

Contains(String str, StringComparison comp)

Here, Contains() is a method of class String.

Contains() Parameters

The Contains() method takes the following parameters:

• str - string which is to be checked
• comp - ignores or considers case sensitivity

Contains() Return Value

The Contains() method returns:

• True - if the string contains the specified substring
• False - if the string doesn't contain the specified substring

Example 1: C# String Contains()

using System;  
namespace CsharpString {  
  class Test {
    public static void Main(string [] args) {
   
      string str = "I love ice cream";  

      bool check;

      // check if str contains "ice cream"
      check = str.Contains("ice cream");
      Console.WriteLine("contains ice cream: " + check);

      // check if str contains "chocolate"
      check = str.Contains("chocolate");
      Console.WriteLine("contains chocolate: " + check);

      // returns true
      check = str.Contains("");
      Console.WriteLine("contains \"\": " + check);

      Console.ReadLine();    
    }
  } 
}

Output

contains ice cream: True
contains chocolate: False
contains "": True

Here,

• str.Contains("ice cream") - returns True as str contains "ice cream"
• str.Contains("chocolate") - returns False as str does not contain "chocolate"
• str.Contains("") - empty string always returns True

Example 2: Contains() With if...else

using System;  
namespace CsharpString {  
  class Test {
    public static void Main(string [] args) {
   
      string str = "Ice cream"; 
    
      // checks if str contains "ice"
      if(str.Contains("ice"))
 {
        Console.WriteLine("str contains ice");
      }

      else {
        Console.WriteLine("str does not contain ice");
      }

      Console.ReadLine();    
    }
  } 
}

Output

str does not contain ice

In the above example, str.Contains("ice") returns False because the method Contains() is case sensitive.

Example 3: C# String Contains() Ignore Case

We can also ignore case sensitivity while using Contains().

using System;  
namespace CsharpString {  
  class Test {
    public static void Main(string [] args) {
   
      string str = "I love ice cream";  

      bool check;
   
      // considers case sensitivity
      check = str.Contains("Ice cream", StringComparison.Ordinal);
      Console.WriteLine("considers case sensitivity: " + check);

      // ignores case sensitivity
      check = str.Contains("Ice cream", StringComparison.OrdinalIgnoreCase);
      Console.WriteLine("ignores case sensitivity: " + check);

      Console.ReadLine();    
    }
  } 
}

Output

considers case sensitivity: False
ignores case sensitivity: True

Here,

• StringComparison.Ordinal - considers the letter case
• StringComparison.OrdinalIgnoreCase - ignores the letter case