Vector Datatype

Dynamic Arrays

Unlike Arrays no need to initialize the size of the array.

// Vector

fn main(){
    let mut my_vec = Vec::new();
    my_vec.push("Rachel");
    my_vec.push("Monica");
    my_vec.push("Phoebe");
    
    println!("{:?}",my_vec);
       
}

fn main(){
    let mut my_vec = Vec::new();
    my_vec.push("Rachel");
    my_vec.push("Monica");
    my_vec.push("Phoebe");
    
    println!("{:?},{:p},{:p}",my_vec,&my_vec,my_vec.as_ptr());
       
}

Vector with Datatype

// This vector is initialized with i32 datatype.
// This code will result in error.

fn main(){
    let mut my_vec: Vec<i32> = Vec::new();
    
    my_vec.push("Rachel");
    my_vec.push("Monica");
    my_vec.push("Phoebe");
    
    println!("{:?}",my_vec);
    
}

// Storing String Literal in String Object

fn main(){
    let mut my_vec: Vec<String> = Vec::new();
    my_vec.push("Rachel");
    my_vec.push("Monica");
    my_vec.push("Phoebe");
   
    println!("{:?}",my_vec);  
}

// &str

fn main(){
    let mut my_vec: Vec<&str> = Vec::new();
    my_vec.push("Rachel");
    my_vec.push("Monica");
    my_vec.push("Phoebe");
    
    println!("{:?}",my_vec);
    
}

// String

fn main(){
    let mut my_vec: Vec<String> = Vec::new();
    my_vec.push("Rachel".to_string());
    my_vec.push("Monica".to_string());
    my_vec.push("Phoebe".to_string());
   
    println!("{:?}",my_vec);  
}

Vec Macro for initializing

// Vec macro

fn main(){
    //Using vec macro
    let my_vec = vec![2,4,6,8,10,12,14,16];
    
    let one = &my_vec[2..6];
    let two = &my_vec[2..];
    let three = &my_vec[..6];
    let four = &my_vec[..];
    
    println!("{:?}",one);
    println!("{:?}",two);
    println!("{:?}",three);
    println!("{:?}",four);
}

Capacity() vs Len()

// capacity() number of elements the vector can hold (without reallocating memory). This is usually larger than or equal to the number of elements currently in the vector.
// len() number of elements

fn main(){
    let mut my_vec: Vec<String> = Vec::new();
    my_vec.push("Rachel".to_string());
    my_vec.push("Monica".to_string());
    my_vec.push("Phoebe".to_string());

    println!("{:?}",my_vec);
    //Initial capacity was 4
    println!("{}",my_vec.capacity());
    println!("{}",my_vec.len());
    
    // now Rust is allocating space 100 more elements. Now the total capacity will be 103. 
    my_vec.reserve(100);
    
    println!("{}",my_vec.capacity());
    println!("{}",my_vec.len());
    
}

Convert Array to Vector

fn main(){
    let arr1 = [1,2,3,4];
    let my_vec:Vec<i8> = arr1.into();
    let my_vec1:Vec<_> = arr1.into();
    
    println!("{:?},{:?},{:?}",arr1,my_vec,my_vec1);
    
    print_type_of(&arr1);
    print_type_of(&my_vec);
    print_type_of(&my_vec1);
}


fn print_type_of<T>(_: &T) {
    println!("{}", std::any::type_name::<T>())
}

Sort the Vector

fn main() {
    let mut vec = vec![14, 33, 12, 56, 3223, 2211, 9122, 3, 299, 67];
    vec.sort();
    println!("Sorted: {:?}", vec)
}