composer

1、可以看到报错原因是：系统中缺少扩展php extension fileinfo；

报错( - intervention/image 2.4.2 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.)

解决方案：打开php.ini配置文件，打开extension=php_fileinfo.dll扩展项，保存重启apache；

　　开启扩展后查看方式：php -m |grep fileinfo;    php -m |grep gd;

2、需要选择合适的版本，

报错(  Could not find a version of package wangningkai/var-dumper matching your minimum-stability (stable). Require it with an explicit version constraint allowing its desired stability.)

解决方案：下载需要加上参数：D:\code\test\dumper>composer require wangningkai/var-dumper  dev-master