C# Strings: A Complete Guide for Beginners
In C#, strings are used to store sequences of characters like names, sentences, file paths, and more. They are one of the most essential data types used in everyday programming.
What is a String?
In C#, a string is a collection of characters enclosed in double quotes ("). It’s part of the
System.String class.
Example:
string greeting = "Hello, World!";
string empty = ""; // empty string
Key Points About C# Strings
- Strings are immutable: once created, they cannot be changed.
- All string operations return a new string.
stringis an alias forSystem.String.
Common String Operations
1. Concatenation
Combining strings using the + operator.
string firstName = "John";
string lastName = "Doe";
string fullName = firstName + " " + lastName;
Console.WriteLine(fullName); // John Doe
2. String Interpolation
Easier way to combine variables with strings.
string name = "Alice";
int age = 25;
string info = $"Name: {name}, Age: {age}";
3. Common String Methods
| Method | Description | Example |
|---|---|---|
ToUpper() |
Converts to uppercase | "hello".ToUpper() → "HELLO" |
ToLower() |
Converts to lowercase | "HELLO".ToLower() → "hello" |
Contains("text") |
Checks if substring exists | "welcome".Contains("come") → true |
Replace("a", "b") |
Replaces characters | "car".Replace("c", "b") → "bar" |
Substring(0, 4) |
Extracts a portion of the string | "Example".Substring(0, 4) → "Exam" |
Trim() |
Removes whitespace from both ends | " hi ".Trim() → "hi" |
Split(' ') |
Splits string by character or word | "one two".Split(' ') → ["one", "two"] |
IndexOf("word") |
Returns index of first occurrence | "hello".IndexOf("e") → 1 |
https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/strings/
Special String Types
Verbatim Strings (@)
Used for file paths or strings with escape characters.
string path = @"C:\Users\John\Documents";
Escape Sequences
| Sequence | Description |
|---|---|
\n |
New line |
\t |
Tab space |
\\ |
Backslash |
\" |
Double quote |
Example -
string message = "Hello\nWorld!";
String vs StringBuilder
Since strings are immutable, use StringBuilder for efficient modifications:
using System.Text;
StringBuilder sb = new StringBuilder("Hello");
sb.Append(" World");
Console.WriteLine(sb.ToString()); // Hello World
Summary
| Feature | Example |
|---|---|
| Declare a string | string name = "Bob"; |
| Combine strings | "Hello" + " " + "World" |
| String interpolation | $"Hi, {name}" |
| Access length | name.Length |
| Modify with methods | name.ToUpper(), name.Replace() |
| Use escape characters | "Line1\nLine2" |
| Handle efficiently | StringBuilder |
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