Macro into_vec

macro_rules! into_vec {
    (
    $( $key : expr ),* $( , )?
  ) => { ... };
}

Creates a Vec from a list of elements.

The into_vec! macro simplifies the creation of a Vec with initial elements. Elements passed to the macro are automatically converted into the vector’s element type using .into(), making it convenient to use literals or values of different, but convertible types.

Note: The into_vec! macro utilizes the .into() method to convert each element into the target type of the Vec. Therefore, the elements must be compatible with the Into<T> trait for the type T used in the Vec. Also, this means that sometimes you must specify the type of collection’s items.

Origin

This collection is reexported from alloc.

Syntax

The macro can be called with a comma-separated list of elements. A trailing comma is optional.

// Vec of i32
let vec1 : Vec< i32 > = into_vec!( 1, 2, 3, 4, 5 );

// Vec of String
let vec2 : Vec< String > = into_vec!{ "hello", "world", "rust" };

// With trailing comma
let vec3 : Vec< f64 > = into_vec!( 1.1, 2.2, 3.3, );

Parameters

• $( $key : expr ),* $( , )?: A comma-separated list of elements to insert into the Vec. Each element can be of any type that implements the Into<T> trait, where T is the type stored in the Vec.

Returns

Returns a Vec containing all the specified elements. The capacity of the vector is automatically determined based on the number of elements provided.

Example

Basic usage with integers:

let vec : Vec< i32 > = into_vec!( 1, 2, 3 );
assert_eq!( vec[ 0 ], 1 );
assert_eq!( vec[ 1 ], 2 );
assert_eq!( vec[ 2 ], 3 );

Example

Using with different types that implement Into<T>:

let words : Vec< String > = into_vec!( "alpha", "beta", "gamma" );
assert_eq!( words[ 0 ], "alpha" );
assert_eq!( words[ 1 ], "beta" );
assert_eq!( words[ 2 ], "gamma" );

Example

Creating a Vec of String from string literals and String objects:

let mixed : Vec< String > = into_vec!{ "value", "another value".to_string() };
assert_eq!( mixed[ 0 ], "value" );
assert_eq!( mixed[ 1 ], "another value" );