Variables, Mut & Shadowing

Author: hitesh-bhatnagar

examples/01_variables.rs

@@ -1,12 +1,58 @@
+// TO RUN THE EXAMPLE : cargo run --example 01_variables
+
 fn main() {
 
-    // Part 1 : Immutable vs Mutable Variables
+    // PART 1 : Immutable vs Mutable Variables
     let x = 5;
     let mut y = 10;
     y = 20 ;
 
     println!("x = {} ", x);
     println!("y = {} ", y);
 
-    // 
+    // PART 2 : Data Types
+    
+    let age: u32 = 25; // unsigned 32-bit integer -- can't be negative
+    let count: i32 = 100; // signed 32=bit integer -- can be negative or positive
+    let big: i64 = 1_000_000; // underscores make numbers readable
+    let pi: f64 = 3.14159; // float
+    let flag: bool = true; // boolean
+    let letter: char = 'A'; // character
+    let name: &str = "Hitesh Bhatnagar"; // fixed text known at compile time
+    
+    let greeting: String = String::from("Hello, Universe"); // owned text - flexible
+    
+    // PART 3: Shadowing 
+    
+    // shadowing allows redeclare a variable with the same name
+    // Each let x creates a BRAND NEW VARIABLE
+    let x = 5;
+    let x = x*2; // new x created, old x is deleted
+    let x = x+3; // another new x
+    
+    println!("Shadowed x  = {}", x); // 13
+    
+    let spaces = "   "; // &str type
+    let spaces = spaces.len(); // now usize ( a number ) -- totally fine 
+    println!("spaces = {}", spaces); // 3
+    
+    // PART 4: mut V/S Shadowing 
+    
+    let mut score = 0;
+    score = 20;
+    println!(" score = {}", score);
+    
+    // Shadowing => Creates new variable, can change VALUE & TYPE
+    let status = "inactive";
+    println!("status = {}", status);
+    let status = true; // changes type from &str to bool
+    println!("status = {}", status);
+    
+    // PART5 : Constants
+    
+    const euler_num: f32 = 2.71828;
+    println!("Max euler_num= {}", euler_num );
+    
+    
+    
 }

src/main.rs

@@ -0,0 +1,3 @@
+fn main(){
+    println!("Happy Learning :)")
+}