C# String Methods

What You’ll Find Here

The System.String class provides methods for comparing text, searching substrings, joining strings, formatting output, copying characters, and reading runtime metadata. This page is your central hub: browse every method in our tutorial series, jump to full guides with examples and output, and learn patterns that work in real C# programs.

Introduction

In C#, strings are instances of System.String (alias string). You call methods with dot notation: text.Contains("C#"), name.Equals("Admin"), file.EndsWith(".cs"). Several helpers are static and live on the class: String.Compare(...), String.Concat(...), and String.Format(...).

Strings are immutable—once created, their characters cannot change. Methods like Concat() and Format() return new string objects rather than modifying the original.

🚀 Usage Tips

• Pick the right compare — use CompareOrdinal() for file paths and identifiers; use Compare() with culture for user-visible sort order.
• Null-safe checks — calling instance methods on null throws NullReferenceException. Guard with string.IsNullOrEmpty(text) first.
• Choose the right search — Contains() for presence, EndsWith() for suffixes like file extensions.
• Prefer StringBuilder in loops — repeated + or Concat() in tight loops allocates many strings; build with StringBuilder instead.
• Static vs instance — Compare(), Concat(), Format(), and Copy() are static; most other methods run on a string variable.
• Read the tutorial — each linked method page includes syntax, five examples, a quick reference table, and FAQs.

📝 How to Call a String Method

Instance methods run on a string variable; static methods use the String class name:

stringReference.MethodName(arguments)   // instance
String.StaticMethod(arguments)          // static

Common Patterns

Instance Methods vs Static Methods

Most String methods run on an existing string object. Static methods belong to the String class and do not require a particular string instance to start with.

string greeting = "Hello";
bool found = greeting.Contains("ell");           // instance: search
bool match = greeting.Equals("Hello");           // instance: compare
string joined = String.Concat(greeting, ", C#!"); // static: join

string formatted = String.Format("Count: {0}", 42);  // static: template
string copy = String.Copy(greeting);                 // static: duplicate