Pattern matching add

11. pattern_matching.md

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+### 11. Pattern Matching: Unveiling the Magic of Rust's Match Operator
+
+#### Introduction to Pattern Matching
+
+Pattern matching in Rust is like solving a puzzle. It allows you to match the structure of data against patterns you define, enabling powerful and expressive control flow in your code. Whether you're handling enums, tuples, or complex data structures, pattern matching has got you covered.
+
+#### The Basics of Match: Matching Against Patterns
+
+The `match` keyword is Rust's Swiss Army knife for pattern matching. It allows you to match a value against a series of patterns and execute different code blocks based on the match. With `match`, you can handle a wide range of scenarios with elegance and precision.
+
+```rust
+let x = 5;
+match x {
+    0 => println!("It's zero!"),
+    1 | 2 => println!("It's one or two!"),
+    _ => println!("It's something else!"),
+}
+```
+
+#### Patterns Galore: From Enums to Structs
+
+Pattern matching shines brightest when dealing with enums and structs. It allows you to destructure complex data types and extract values with ease. Whether you're handling Option types, parsing JSON, or processing network packets, pattern matching is your best friend.
+
+```rust
+enum Coin {
+    Penny,
+    Nickel,
+    Dime,
+    Quarter(UsState),
+}
+
+fn value_in_cents(coin: Coin) -> u8 {
+    match coin {
+        Coin::Penny => 1,
+        Coin::Nickel => 5,
+        Coin::Dime => 10,
+        Coin::Quarter(state) => {
+            println!("State quarter from {:?}!", state);
+            25
+        }
+    }
+}
+```
+
+#### Exhaustive Matches and Wildcards: Covering All Bases
+
+Rust's exhaustive pattern matching ensures that you cover all possible cases, leaving no stone unturned. With the `_` wildcard, you can handle any unexpected cases gracefully, preventing bugs and surprises in your code.
+
+```rust
+let number = Some(7);
+match number {
+    Some(5) => println!("It's five!"),
+    Some(_) => println!("It's some other number!"),
+    None => println!("It's none!"),
+}
+```
+
+#### Binding and Guard Clauses: Adding Flexibility to Matches
+
+Pattern matching in Rust isn't just about matching; it's about binding and guarding too. With binding, you can extract values from patterns and use them in subsequent code blocks. Guard clauses allow you to add additional conditions to your matches, making them even more powerful.
+
+```rust
+let num = Some(7);
+match num {
+    Some(x) if x < 5 => println!("Less than five: {}", x),
+    Some(x) => println!("Greater than or equal to five: {}", x),
+    None => println!("It's none!"),
+}
+```
+
+#### Best Practices
+
+- Use pattern matching to handle complex control flow scenarios with clarity and precision.
+- Leverage exhaustive matches to cover all possible cases and prevent unexpected behavior.
+- Embrace binding and guard clauses to add flexibility and expressiveness to your matches.
+
+#### Real-World Example
+
+Imagine you're building a chatbot in Rust. You use pattern matching to parse user inputs, match them against predefined patterns, and generate appropriate responses. With pattern matching, your chatbot can handle a wide range of user inputs, from simple greetings to complex queries, with ease and efficiency.
+
+#### Conclusion
+
+Pattern matching is like a secret weapon in your Rust programming arsenal, enabling you to tackle complex control flow scenarios with elegance and clarity. By mastering the art of pattern matching, you'll become a more confident and proficient Rust programmer, capable of solving a wide range of coding puzzles with finesse and flair.