The following functions don't work because they contain a restricted keyword:
[spoiler]Because of 'try': //country
'geoip_country_code_by_name','geoip_country_name_by_name','geoip_time_zone_by_country_and_region'
//date time Because of 'parse':
'date_parse' Because of 'open':
'timezone_open' Because of 'mod':
'date_modify' Because of 'INF':
'date_sun_info' , Because of 'val':
'date_interval_format', Because of 'E_PARSE':
'date_parse',
//math Because of 'mod':
'fmod' Because of 'ini':
'is_finite',
'is_infinite' Because of 'T_SR':
'mt_srand', Because of 'val':
'lcg_value',
//string Because of 'ext':
'similar_text' Because of 'split':
'chunk_split','str_split', Because of 'sprintf':
'vsprintf', Because of 'fprintf':
'vfprintf' ,
//arrays Because of 'ext':
'next', Because of 'T_AS'
'array_intersect_assoc', Because of 'val':
'array_count_values' ,
'array_values',
//variables Because of 'is_a':
'is_array',
//regular expressions Because of 'split':
'preg_split', Because of 'error':
'preg_last_error', Because of 'call':
'preg_replace_callback',
[/spoiler]
That leaves us with the following functions that should work:
[spoiler]
//math
'abs','acos','acosh','asin','asinh','atan2','atan' ,'atanh','base_convert','bindec','ceil','cos','cosh',
'decbin','dechex','decoct','deg2rad','exp','expm1',' floor','getrandmax','hexdec','hypot','is_nan',
'log10','log1p','log' ,'max','min','mt_getrandmax','mt_rand','octdec','pi','pow','rad2deg','rand',
'round','sin' ,'sinh','sqrt','srand','tan','tanh',
//string
'print','echo','count_chars','crc32','crypt','explode' ,'htmlspecialchars','htmlspecialchars_ decode',
'get_ html_ translation_ table','printf','implode','md5','number_format','ord',' chr','chop','lcfirst',
'str_pad','str_ireplace','str_repeat','str_replace' ,'str_rot13','str_shuffle','str_word_count',
'strcasecmp','strchr','strcmp','strip_tags', 'strcspn','stripos','stripslashes','stristr','strlen',
'strnatcasecmp','strnatcmp','strncasecmp','strncmp', 'strpbrk','strpos','strrchr','strrev','strrev',
'strrpos','strspn','strstr','strtok','strtolower','strtoupper' ,'strtr','substr_compare','substr_count',
'substr_replace','substr','trim','ucfirst','ucwords','vprintf','wordwrap',
//arrays
'array_change_key_case','array_chunk','array_combine','array_diff_assoc','array_diff_key',
'array_diff','array_fill_keys','array_fill','array_flip','array_intersect_key','array_intersect',
'array_keys','array_merge_recursive','array_merge' ,'array_multisort','array_pad','array_pop',
'array_product','array_push','array_rand','array_replace_recursive' ,'array_replace',
'array_reverse','array_search','array_shift','array_slice','array_splice' ,'array_sum','array_unique',
'array_unshift','array','arsort','asort','count','current','each','end','in_array','key','krsort','ksort','list',
'natcasesort','natsort','pos','prev','range','reset','rsort','shuffle','sizeof' ,'sort','uasort',
//variables
'is_binary','is_bool','is_float','is_double',' is_int','is_integer','is_null','is_numeric','is_string','is_scalar',
'isset','serialize','unserialize','unset'
//date time
'date','time','date_add','date_create','date_diff','date_format' ,'date_offset_get','date_sub',
'date_sunrise','date_sunset','date_timestamp_get','date_timezone_get','getdate','gettimeofday',
'gmdate','gmmktime','gmstrftime','idate','localtime','microtime' ,'mktime','strftime','strptime','strtotime',
'timezone_location_get','timezone_name_get','timezone_offset_get', ,'timezone_transitions_get',
//encrypt
'mcrypt_ecb','mcrypt_cfb','mcrypt_cbc','mcrypt_ofb','hash',
//url
'url','urldecode','urlencode','base64_decode','base64_encode' ,
//regular expressions
'preg_filter','preg_match_all','preg_match','preg_quote' ,'preg_replace',
[/spoiler]