PHP 내장함수

mysql_는 PHP7에서 제거됨 → mysqli_ 또는 PDO.

문자열

strlen, strpos, strrpos, substr, substr_replace, str_replace, str_repeat
strtolower, strtoupper, ucfirst, ucwords, trim/ltrim/rtrim, strrev
strcmp, strcasecmp, strstr, stristr, strchr, strrchr, strtok, strtr
explode, implode/join, sprintf/printf, nl2br, strip_tags
htmlspecialchars, htmlentities, addslashes/stripslashes, addcslashes/stripcslashes

배열

array, array_merge, array_push/pop, array_shift/unshift, array_splice
array_keys, array_values, array_flip, array_reverse, array_walk
sort/rsort/asort/arsort/ksort/krsort/uasort/uksort/usort
in_array, count/sizeof, range, shuffle, compact/extract
current/next/prev/reset/end/key

타입

isset, empty, unset, gettype, settype
is_array, is_string, is_int, is_float, is_object
intval, strval, doubleval

수학

abs, ceil, floor, round, pow, sqrt, max, min
sin/cos/tan/asin/acos/atan, log/log10, pi
rand/mt_rand, srand/mt_srand, getrandmax/mt_getrandmax
decbin/dechex/decoct, bindec/hexdec/octdec, base_convert

날짜·파일·기타

date, mktime
fopen/fclose, feof, fgets, fgetc, fgetcsv
copy, chmod, chown, chgrp, basename, dirname
md5, base64_encode/decode
urlencode/urldecode, rawurlencode/rawurldecode
parse_url, parse_str
session_start, session_id, session_destroy, session_save_path

GD

imagecreate, imagecreatefromgif, imagecolorallocate, imagefill
imageline/imagerectangle/imagearc/imagepolygon
imagestring/imagettftext, imagegif, imagedestroy

MySQL (구확장, PHP7+ 제거)

mysql_connect, mysql_select_db, mysql_query
mysql_fetch_array/_object/_row, mysql_num_rows/_fields
mysql_insert_id, mysql_close