first commit

functions/src/main.rs

@@ -0,0 +1,20 @@
+/*
+function is a block or reusable code.
+defining the function if fn keyword, and every Rust programs starts with this main function.
+*/
+fn main() {
+    greet();
+    println!("{}", multiple(5, 5));
+}
+
+fn greet() {
+    println!("namaste!")
+}
+
+/*
+[parameterized function]
+no type given is directly compliation error, so type annotatin is important
+*/
+fn multiple(a: i32, b: i32) -> i32 {
+    a * b
+}