How to Compare Strings in C#: Syntax and Examples

In C#, you can compare strings using the == operator, the Equals() method, or the String.Compare() method. The == operator checks if two strings have the same value, while Equals() can be used with options like case sensitivity. String.Compare() returns an integer indicating the lexical order of the strings.

Syntax

Here are the common ways to compare strings in C#:

• string1 == string2: Checks if both strings have the same value.
• string1.Equals(string2): Compares strings for equality, can specify case sensitivity.
• String.Compare(string1, string2): Returns an integer indicating order (<0, 0, >0).

csharp

bool areEqual = string1 == string2;
bool areEqualMethod = string1.Equals(string2);
int comparison = String.Compare(string1, string2);

Example

This example shows how to compare strings using ==, Equals() with case sensitivity, and String.Compare().

csharp

using System;

class Program
{
    static void Main()
    {
        string a = "Hello";
        string b = "hello";

        // Using == operator
        Console.WriteLine(a == b); // False

        // Using Equals with case sensitivity
        Console.WriteLine(a.Equals(b)); // False

        // Using Equals ignoring case
        Console.WriteLine(a.Equals(b, StringComparison.OrdinalIgnoreCase)); // True

        // Using String.Compare
        int result = String.Compare(a, b, StringComparison.OrdinalIgnoreCase);
        if (result == 0)
            Console.WriteLine("Strings are equal ignoring case.");
        else if (result < 0)
            Console.WriteLine("a is less than b.");
        else
            Console.WriteLine("a is greater than b.");
    }
}

Output

False
False
True
Strings are equal ignoring case.

Common Pitfalls

Common mistakes when comparing strings in C# include:

• Using == when you need case-insensitive comparison.
• Not specifying StringComparison in Equals() or Compare(), which defaults to case-sensitive and culture-sensitive comparison.
• Using ReferenceEquals() which checks if two variables point to the same object, not if their text is equal.

csharp

string x = "Test";
string y = "test";

// Wrong: case-sensitive comparison
bool wrong = x == y; // false

// Right: case-insensitive comparison
bool right = x.Equals(y, StringComparison.OrdinalIgnoreCase); // true

Quick Reference

Method	Description	Case Sensitivity
== operator	Checks if two strings have the same value	Case-sensitive
Equals()	Checks equality, can specify case sensitivity	Case-sensitive by default, can ignore case with parameter
String.Compare()	Compares lexical order, returns int (<0, 0, >0)	Case-sensitive by default, can ignore case with parameter

Key Takeaways

Use == for simple, case-sensitive string equality checks.

Use Equals() with StringComparison to control case sensitivity.

Use String.Compare() to determine lexical order between strings.

Avoid ReferenceEquals() for string content comparison.

Always specify StringComparison to avoid culture and case issues.