To enable extensions, verify that they are enabled in your .ini

  Problem 1
    - laravel/installer v1.4.1 requires ext-zip * -> the requested PHP extension zip is missing from your system.
    - laravel/installer v1.4.0 requires ext-zip * -> the requested PHP extension zip is missing from your system.
    - Installation request for laravel/installer ^1.4 -> satisfiable by laravel/installer[v1.4.0, v1.4.1].

  To enable extensions, verify that they are enabled in your .ini files:
    - /etc/php/7.0/cli/php.ini
    - /etc/php/7.0/cli/conf.d/10-mysqlnd.ini
    - /etc/php/7.0/cli/conf.d/10-opcache.ini
    - /etc/php/7.0/cli/conf.d/10-pdo.ini
    - /etc/php/7.0/cli/conf.d/20-apcu.ini
    - /etc/php/7.0/cli/conf.d/20-calendar.ini
    - /etc/php/7.0/cli/conf.d/20-ctype.ini
    - /etc/php/7.0/cli/conf.d/20-exif.ini
    - /etc/php/7.0/cli/conf.d/20-fileinfo.ini
    - /etc/php/7.0/cli/conf.d/20-ftp.ini
    - /etc/php/7.0/cli/conf.d/20-gd.ini
    - /etc/php/7.0/cli/conf.d/20-gettext.ini
    - /etc/php/7.0/cli/conf.d/20-iconv.ini
    - /etc/php/7.0/cli/conf.d/20-json.ini
    - /etc/php/7.0/cli/conf.d/20-mysqli.ini
    - /etc/php/7.0/cli/conf.d/20-pdo_mysql.ini
    - /etc/php/7.0/cli/conf.d/20-phar.ini
    - /etc/php/7.0/cli/conf.d/20-posix.ini
    - /etc/php/7.0/cli/conf.d/20-readline.ini
    - /etc/php/7.0/cli/conf.d/20-shmop.ini
    - /etc/php/7.0/cli/conf.d/20-sockets.ini
    - /etc/php/7.0/cli/conf.d/20-sysvmsg.ini
    - /etc/php/7.0/cli/conf.d/20-sysvsem.ini
    - /etc/php/7.0/cli/conf.d/20-sysvshm.ini
    - /etc/php/7.0/cli/conf.d/20-tokenizer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.
  
  ----------------------------------------------------------------------------------------------
  
    sudo apt-get update
    
    sudo apt-get install mcrypt php7.0-mcrypt
    
    sudo apt-get upgrade
    
    sudo apt-get install php-mbstring
     
    sudo apt-get install phpunit
    
    sudo apt-get install php7.0-zip
    
    sudo apt-get install php7.0-zip
    
    
     

You have to enable ";extension=gmp" into "extension=gmp" in C:\xampp\php\php.ini.

merci sa marche parfaitement

any solution with this error? I have this error when I try to install composer in my laravel project

Try to follow up with these commands and if you still get any extension errors then just install that extension: sudo apt-get install php7.0-{extension-name}

    sudo apt-get update
    
    sudo apt-get install mcrypt php7.0-mcrypt
    
    sudo apt-get upgrade
    
    sudo apt-get install php-mbstring
     
    sudo apt-get install phpunit
    
    sudo apt-get install php7.0-zip
    
    sudo apt-get install php7.0-zip
    ```