some more learning programms

functions.rs

@@ -0,0 +1,60 @@
+// here plays the music!
+// Syntax & Semantic
+
+
+// main function
+fn main() { 
+    let x: i32 = 5; // set x unmutable, integer 5
+    
+    let mut y = 7; // set y mutable 5 (here an integer)
+    println!("The value of y is: {}", y);
+    y = 4; // change y
+    println!("The value of y is: {}", y);
+    
+    {
+            println!("The value of x is: {}", x);
+            let x: i32 = 7; // changing x, only inside loop
+            println!("The value of x is: {}", x);
+    }
+    let y = "I'm a text now!"; // change y again (here as text)
+    println!("The value of y is: {} ", y);
+    
+    println!("The value of x is: {}", x);
+
+    print_number(88); // call function
+    sum(3, 5);
+    let a = add_one(x);
+    
+    let z = (x + 2);
+    println!("New values a: {}, z: {}", a, z);
+
+    // variable bindings with point to function
+    let f: fn(i32) -> i32 = add_one; // without type inference
+    //let f = add_one; // with type inference
+    let six = f(5); // call function
+    println!("called function says: {}", six);
+}
+
+
+// declaring function
+
+// function for printing numbers
+fn print_number(x: i32) {
+    println!("x is: {}", x);
+}
+
+// function for adding two numbers
+fn sum(x: i32, y: i32) {
+    println!("sum is: {}", x + y); // print sum of numbers
+}
+
+// adding 1 to number
+fn add_one(i: i32) -> i32 { // -> i32 declairs return of function
+    i + 1 // here no ';' -> Rust = expression based language 
+    // x + 1; doesn't retourn value
+}
+
+// never returning function
+fn diverges() -> ! {
+    panic!("This function never returns!"); // macro -> causes the current thread of execution to crash
+}