echo "<pre>";
print_r(get_extension_funcs("standard"));
echo "</pre>";
/*
run:
Array
(
[0] => constant
[1] => bin2hex
[2] => hex2bin
[3] => sleep
[4] => usleep
[5] => time_nanosleep
[6] => time_sleep_until
[7] => strptime
[8] => flush
[9] => wordwrap
[10] => htmlspecialchars
[11] => htmlentities
[12] => html_entity_decode
[13] => htmlspecialchars_decode
[14] => get_html_translation_table
[15] => sha1
[16] => sha1_file
[17] => md5
[18] => md5_file
[19] => crc32
[20] => iptcparse
[21] => iptcembed
[22] => getimagesize
[23] => getimagesizefromstring
[24] => image_type_to_mime_type
[25] => image_type_to_extension
[26] => phpinfo
[27] => phpversion
[28] => phpcredits
[29] => php_sapi_name
[30] => php_uname
[31] => php_ini_scanned_files
[32] => php_ini_loaded_file
[33] => strnatcmp
[34] => strnatcasecmp
[35] => substr_count
[36] => strspn
[37] => strcspn
[38] => strtok
[39] => strtoupper
[40] => strtolower
[41] => strpos
[42] => stripos
[43] => strrpos
[44] => strripos
[45] => strrev
[46] => hebrev
[47] => hebrevc
[48] => nl2br
[49] => basename
[50] => dirname
[51] => pathinfo
[52] => stripslashes
[53] => stripcslashes
[54] => strstr
[55] => stristr
[56] => strrchr
[57] => str_shuffle
[58] => str_word_count
[59] => str_split
[60] => strpbrk
[61] => substr_compare
[62] => utf8_encode
[63] => utf8_decode
[64] => strcoll
[65] => money_format
[66] => substr
[67] => substr_replace
[68] => quotemeta
[69] => ucfirst
[70] => lcfirst
[71] => ucwords
[72] => strtr
[73] => addslashes
[74] => addcslashes
[75] => rtrim
[76] => str_replace
[77] => str_ireplace
[78] => str_repeat
[79] => count_chars
[80] => chunk_split
[81] => trim
[82] => ltrim
[83] => strip_tags
[84] => similar_text
[85] => explode
[86] => implode
[87] => join
[88] => setlocale
[89] => localeconv
[90] => nl_langinfo
[91] => soundex
[92] => levenshtein
[93] => chr
[94] => ord
[95] => parse_str
[96] => str_getcsv
[97] => str_pad
[98] => chop
[99] => strchr
[100] => sprintf
[101] => printf
[102] => vprintf
[103] => vsprintf
[104] => fprintf
[105] => vfprintf
[106] => sscanf
[107] => fscanf
[108] => parse_url
[109] => urlencode
[110] => urldecode
[111] => rawurlencode
[112] => rawurldecode
[113] => http_build_query
[114] => readlink
[115] => linkinfo
[116] => symlink
[117] => link
[118] => unlink
[119] => exec
[120] => system
[121] => escapeshellcmd
[122] => escapeshellarg
[123] => passthru
[124] => shell_exec
[125] => proc_open
[126] => proc_close
[127] => proc_terminate
[128] => proc_get_status
[129] => proc_nice
[130] => rand
[131] => srand
[132] => getrandmax
[133] => mt_rand
[134] => mt_srand
[135] => mt_getrandmax
[136] => random_bytes
[137] => random_int
[138] => getservbyname
[139] => getservbyport
[140] => getprotobyname
[141] => getprotobynumber
[142] => getmyuid
[143] => getmygid
[144] => getmypid
[145] => getmyinode
[146] => getlastmod
[147] => base64_decode
[148] => base64_encode
[149] => password_hash
[150] => password_get_info
[151] => password_needs_rehash
[152] => password_verify
[153] => convert_uuencode
[154] => convert_uudecode
[155] => abs
[156] => ceil
[157] => floor
[158] => round
[159] => sin
[160] => cos
[161] => tan
[162] => asin
[163] => acos
[164] => atan
[165] => atanh
[166] => atan2
[167] => sinh
[168] => cosh
[169] => tanh
[170] => asinh
[171] => acosh
[172] => expm1
[173] => log1p
[174] => pi
[175] => is_finite
[176] => is_nan
[177] => is_infinite
[178] => pow
[179] => exp
[180] => log
[181] => log10
[182] => sqrt
[183] => hypot
[184] => deg2rad
[185] => rad2deg
[186] => bindec
[187] => hexdec
[188] => octdec
[189] => decbin
[190] => decoct
[191] => dechex
[192] => base_convert
[193] => number_format
[194] => fmod
[195] => intdiv
[196] => inet_ntop
[197] => inet_pton
[198] => ip2long
[199] => long2ip
[200] => getenv
[201] => putenv
[202] => getopt
[203] => sys_getloadavg
[204] => microtime
[205] => gettimeofday
[206] => getrusage
[207] => hrtime
[208] => uniqid
[209] => quoted_printable_decode
[210] => quoted_printable_encode
[211] => convert_cyr_string
[212] => get_current_user
[213] => set_time_limit
[214] => header_register_callback
[215] => get_cfg_var
[216] => get_magic_quotes_gpc
[217] => get_magic_quotes_runtime
[218] => error_log
[219] => error_get_last
[220] => error_clear_last
[221] => call_user_func
[222] => call_user_func_array
[223] => forward_static_call
[224] => forward_static_call_array
[225] => serialize
[226] => unserialize
[227] => var_dump
[228] => var_export
[229] => debug_zval_dump
[230] => print_r
[231] => memory_get_usage
[232] => memory_get_peak_usage
[233] => register_shutdown_function
[234] => register_tick_function
[235] => unregister_tick_function
[236] => highlight_file
[237] => show_source
[238] => highlight_string
[239] => php_strip_whitespace
[240] => ini_get
[241] => ini_get_all
[242] => ini_set
[243] => ini_alter
[244] => ini_restore
[245] => get_include_path
[246] => set_include_path
[247] => restore_include_path
[248] => setcookie
[249] => setrawcookie
[250] => header
[251] => header_remove
[252] => headers_sent
[253] => headers_list
[254] => http_response_code
[255] => connection_aborted
[256] => connection_status
[257] => ignore_user_abort
[258] => parse_ini_file
[259] => parse_ini_string
[260] => is_uploaded_file
[261] => move_uploaded_file
[262] => gethostbyaddr
[263] => gethostbyname
[264] => gethostbynamel
[265] => gethostname
[266] => net_get_interfaces
[267] => dns_check_record
[268] => checkdnsrr
[269] => dns_get_mx
[270] => getmxrr
[271] => dns_get_record
[272] => intval
[273] => floatval
[274] => doubleval
[275] => strval
[276] => boolval
[277] => gettype
[278] => settype
[279] => is_null
[280] => is_resource
[281] => is_bool
[282] => is_int
[283] => is_float
[284] => is_integer
[285] => is_long
[286] => is_double
[287] => is_real
[288] => is_numeric
[289] => is_string
[290] => is_array
[291] => is_object
[292] => is_scalar
[293] => is_callable
[294] => is_iterable
[295] => is_countable
[296] => pclose
[297] => popen
[298] => readfile
[299] => rewind
[300] => rmdir
[301] => umask
[302] => fclose
[303] => feof
[304] => fgetc
[305] => fgets
[306] => fgetss
[307] => fread
[308] => fopen
[309] => fpassthru
[310] => ftruncate
[311] => fstat
[312] => fseek
[313] => ftell
[314] => fflush
[315] => fwrite
[316] => fputs
[317] => mkdir
[318] => rename
[319] => copy
[320] => tempnam
[321] => tmpfile
[322] => file
[323] => file_get_contents
[324] => file_put_contents
[325] => stream_select
[326] => stream_context_create
[327] => stream_context_set_params
[328] => stream_context_get_params
[329] => stream_context_set_option
[330] => stream_context_get_options
[331] => stream_context_get_default
[332] => stream_context_set_default
[333] => stream_filter_prepend
[334] => stream_filter_append
[335] => stream_filter_remove
[336] => stream_socket_client
[337] => stream_socket_server
[338] => stream_socket_accept
[339] => stream_socket_get_name
[340] => stream_socket_recvfrom
[341] => stream_socket_sendto
[342] => stream_socket_enable_crypto
[343] => stream_socket_shutdown
[344] => stream_socket_pair
[345] => stream_copy_to_stream
[346] => stream_get_contents
[347] => stream_supports_lock
[348] => stream_isatty
[349] => fgetcsv
[350] => fputcsv
[351] => flock
[352] => get_meta_tags
[353] => stream_set_read_buffer
[354] => stream_set_write_buffer
[355] => set_file_buffer
[356] => stream_set_chunk_size
[357] => stream_set_blocking
[358] => socket_set_blocking
[359] => stream_get_meta_data
[360] => stream_get_line
[361] => stream_wrapper_register
[362] => stream_register_wrapper
[363] => stream_wrapper_unregister
[364] => stream_wrapper_restore
[365] => stream_get_wrappers
[366] => stream_get_transports
[367] => stream_resolve_include_path
[368] => stream_is_local
[369] => get_headers
[370] => stream_set_timeout
[371] => socket_set_timeout
[372] => socket_get_status
[373] => realpath
[374] => fnmatch
[375] => fsockopen
[376] => pfsockopen
[377] => pack
[378] => unpack
[379] => get_browser
[380] => crypt
[381] => opendir
[382] => closedir
[383] => chdir
[384] => chroot
[385] => getcwd
[386] => rewinddir
[387] => readdir
[388] => dir
[389] => scandir
[390] => glob
[391] => fileatime
[392] => filectime
[393] => filegroup
[394] => fileinode
[395] => filemtime
[396] => fileowner
[397] => fileperms
[398] => filesize
[399] => filetype
[400] => file_exists
[401] => is_writable
[402] => is_writeable
[403] => is_readable
[404] => is_executable
[405] => is_file
[406] => is_dir
[407] => is_link
[408] => stat
[409] => lstat
[410] => chown
[411] => chgrp
[412] => lchown
[413] => lchgrp
[414] => chmod
[415] => touch
[416] => clearstatcache
[417] => disk_total_space
[418] => disk_free_space
[419] => diskfreespace
[420] => realpath_cache_size
[421] => realpath_cache_get
[422] => mail
[423] => ezmlm_hash
[424] => openlog
[425] => syslog
[426] => closelog
[427] => lcg_value
[428] => metaphone
[429] => ob_start
[430] => ob_flush
[431] => ob_clean
[432] => ob_end_flush
[433] => ob_end_clean
[434] => ob_get_flush
[435] => ob_get_clean
[436] => ob_get_length
[437] => ob_get_level
[438] => ob_get_status
[439] => ob_get_contents
[440] => ob_implicit_flush
[441] => ob_list_handlers
[442] => ksort
[443] => krsort
[444] => natsort
[445] => natcasesort
[446] => asort
[447] => arsort
[448] => sort
[449] => rsort
[450] => usort
[451] => uasort
[452] => uksort
[453] => shuffle
[454] => array_walk
[455] => array_walk_recursive
[456] => count
[457] => end
[458] => prev
[459] => next
[460] => reset
[461] => current
[462] => key
[463] => min
[464] => max
[465] => in_array
[466] => array_search
[467] => extract
[468] => compact
[469] => array_fill
[470] => array_fill_keys
[471] => range
[472] => array_multisort
[473] => array_push
[474] => array_pop
[475] => array_shift
[476] => array_unshift
[477] => array_splice
[478] => array_slice
[479] => array_merge
[480] => array_merge_recursive
[481] => array_replace
[482] => array_replace_recursive
[483] => array_keys
[484] => array_key_first
[485] => array_key_last
[486] => array_values
[487] => array_count_values
[488] => array_column
[489] => array_reverse
[490] => array_reduce
[491] => array_pad
[492] => array_flip
[493] => array_change_key_case
[494] => array_rand
[495] => array_unique
[496] => array_intersect
[497] => array_intersect_key
[498] => array_intersect_ukey
[499] => array_uintersect
[500] => array_intersect_assoc
[501] => array_uintersect_assoc
[502] => array_intersect_uassoc
[503] => array_uintersect_uassoc
[504] => array_diff
[505] => array_diff_key
[506] => array_diff_ukey
[507] => array_udiff
[508] => array_diff_assoc
[509] => array_udiff_assoc
[510] => array_diff_uassoc
[511] => array_udiff_uassoc
[512] => array_sum
[513] => array_product
[514] => array_filter
[515] => array_map
[516] => array_chunk
[517] => array_combine
[518] => array_key_exists
[519] => pos
[520] => sizeof
[521] => key_exists
[522] => assert
[523] => assert_options
[524] => version_compare
[525] => ftok
[526] => str_rot13
[527] => stream_get_filters
[528] => stream_filter_register
[529] => stream_bucket_make_writeable
[530] => stream_bucket_prepend
[531] => stream_bucket_append
[532] => stream_bucket_new
[533] => output_add_rewrite_var
[534] => output_reset_rewrite_vars
[535] => sys_get_temp_dir
[536] => dl
[537] => cli_set_process_title
[538] => cli_get_process_title
)
*/
