Don't use substr to get first char of string

apps/files_archive/lib/storage.php

apps/files_external/lib/ftp.php

apps/files_external/lib/swift.php

apps/files_external/lib/webdav.php

apps/user_ldap/lib_ldap.php

lib/app.php

lib/archive/tar.php

lib/archive/zip.php

lib/filesystem.php

lib/filesystemview.php

lib/installer.php

lib/user/database.php

tests/index.php