我需要替换这种字符串：
https://r2---sn-vgqs7nez.c.docs.google.com/
https://r2---sn-testne4.c.docs.google.com/
https://r5---sn-vfghtgh.c.docs.google.com/
到这个
https://redirector.googlevideo.com/
使用php，请帮助我
您可以使用此正则表达式来搜索和替换
$pattern = '/^(https:'/'/)[a-zA-Z0-9'-.]+.docs.google.com'//g';
preg_replace($pattern, 'https://redirector.googlevideo.com/', $yourstring);
证明：http://regexr.com/3d71p