medium.learning_rust.vector..rs

//Creating vectors - 2 ways
let mut a = Vec::new(); //1.with new() keyword
let mut b = vec![]; //2.using the vec! macro

//Creating with data types
let mut a2: Vec<i32> = Vec::new();
let mut b2: Vec<i32> = vec![];
let mut b3 = vec![1i32, 2, 3];//sufixing 1st value with data type

//Creating with data
let mut b4 = vec![1, 2, 3];
let mut b5: Vec<i32> = vec![1, 2, 3];
let mut b6  = vec![1i32, 2, 3];
let mut b7 = vec![0; 10]; //ten zeroes

//Accessing and changing exsisting data
let mut c = vec![5, 4, 3, 2, 1];
c[0] = 1;
c[1] = 2;
//c[6] = 2; can't assign values this way, index out of bounds
println!("{:?}", c); //[1, 2, 3, 2, 1]

//push and pop
let mut d: Vec<i32> = Vec::new();
d.push(1); //[1] : Add an element to the end
d.push(2); //[1, 2]
d.pop(); //[1] : : Remove an element from the end


// 🔎 Capacity and reallocation
let mut e: Vec<i32> = Vec::with_capacity(10);
println!("Length: {}, Capacity : {}", e.len(), e.capacity()); //Length: 0, Capacity : 10

// These are all done without reallocating...
for i in 0..10 {
    e.push(i);
}
// ...but this may make the vector reallocate
e.push(11);