how to install composer in windows 7 code example

Example 1: install composer mac

curl -sS https://getcomposer.org/installer | php
php composer.phar install
mv composer.phar /usr/local/bin/composer
open -e  ~/.zshrc
// or open -e  ~/.bash_profile
alias composer="php /usr/local/bin/composer"

Example 2: how to install composer windows

why is it so hard to install composer every time it's a struggle