What is the correct way to use variables in the terminal?

Question

linux

Good afternoon!
How to write a command so that when creating an arbitrary folder, the next step is to go to it?
what to fix in this code?
mkdir {$s} && cd {$s}

Answer 1

In .bashrc

mkcd() {
    mkdir $1
    cd $1
}

Then in the console you can write like this

~> mkcd foobar
~/foobar>

Example

Answer 2

mkdir "foo" && cd "$_"