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fn main() {
// &str and String
let fixed_str = "Fixed length string";
let mut flexible_str = String::from("This string will grow");
// so what happens if we try to set let this ?
// the fixed_str_v2 will not in type of &str but instead will conveted into String dynamically
// but when we try to reassign a string value to it, it will have warning message in editor
let fixed_str_v2 = String::from("What type of string will this be?");
println!("fixed str v2 {fixed_str_v2}");
// this would be wrong
// fixed_str_v2 = "converted into fix ?";
// Arrays
// this means that we create a flexible array that has been allocated space with 4 elements
// and each element's type is i32
// and even though we call it as the mut array but it's size is fixed
// so every time we try to re-assign it to an new array the size and type should be matched strictially
let mut array_1: [i32; 4] = [1, 2, 3, 4];
//this cannot work, because it requires 4 elements
// array_1 = [1, 2];
// println!(array_1);
// this should work, because we apply array by 'mut' so re-assign it is ok
array_1 = [1, 2, 3, 4];
// here we use a lamda to iterate each element in the mutable array
array_1.iter().for_each(|val| println!("{val}"));
println!("{:?}", array_1);
let array_2 = [1, 4, 6, 7, 54, 3];
// Vectors
let vec_1: Vec<i32> = vec![4, 5, 6, 7];
let num = vec_1[3];
println!("{num}");
// Tuples
let my_info = ("Salary", 3728930, "Age", 39);
let salary_value = my_info.1;
let age = my_info.3;
let (salary_name, salary_value, age_name, age_value) = my_info;
println!("{age_value}");
println!("my info is : {:?}", my_info);
// here we declare an empty tuple
let unit: () = ();
}