What is the String.Contains method in C#?

Overview

In C#, String.Contains() is an instance method of the String class. It is used to find whether a given string contains characters. If it finds a matching substring in this particular string, it returns True. If not, it returns False.

Syntax

public bool Contains (string substring)
// or 
public bool Contains (Char value)

Parameters

String substring // the string to be searched
// or 
Char value // character to be seeked

Returns value

Boolean: It returns True or False based on whether the string contains the given substring.

If the passed substring is null, it throws an ArgumentNullException error.

Code

class HelloWorld
{
    static void Main()
    {
      string text = "The quick brown fox";
      string searchText = "quick"; 
      string searchText1 = "dog";
      bool result = text.Contains(searchText);
      bool result1 = text.Contains(searchText1);
      System.Console.WriteLine("The string '{0}' contains '{1}'? -> '{2}'", text, searchText, result); // True
      System.Console.WriteLine("The string '{0}' contains '{1}'? -> '{2}'", text, searchText1, result1); // False
    }
}

Explanation

  • Line 5–7: We create string objects.
  • Line 9 and 10: We call the String.Contains() method to check whether the substring is present in the original string. It doesn’t return any information about the position of the substring.

  • By default, this method performs a case-sensitive and culture-insensitive comparison.

  • The method has overloaded versions, which takes an additional parameter value of StringComparision enum to indicate what kind of culture-sensitivity and case-sensitivity is to be used while comparing strings.

Boolean Contains(Char, StringComparision)

Boolean Contains(String, StringComparision)

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