C# `String.Contains()` Method: Efficient Substring Searching

Learn how to use C#'s `String.Contains()` method for efficient substring searches. This tutorial explains its functionality, demonstrates its usage with code examples, and highlights its application in various string manipulation and data processing tasks.

Using the C# `String.Contains()` Method

Introduction

The Contains() method in C# is a simple yet powerful way to check if a string contains a specific substring. It returns true if the substring is found, and false otherwise.

Method Signature

The method signature is straightforward:

public bool Contains(String str);

Parameters

• str: The substring you're searching for within the main string.

Return Value

The method returns a Boolean value:

• true: If the substring str is found within the string.
• false: If the substring str is not found.

Example: Checking for Substrings

This example demonstrates how to use Contains() to check if one string contains another.

using System;

public class StringExample {
    public static void Main(string[] args) {
        string s1 = "Hello ";
        string s2 = "He";
        string s3 = "Hi";

        Console.WriteLine(s1.Contains(s2)); // True
        Console.WriteLine(s1.Contains(s3)); // False
    }
}

True
False
        

Explanation

The code checks if s1 contains s2 ("He") and s3 ("Hi"). The first check returns true because "He" is a substring of "Hello ", while the second returns false.

Conclusion

The Contains() method is a simple and efficient way to perform substring checks in C#. It's a fundamental tool for string manipulation and data validation.