目录
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PHP Reference
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PHP Array
- PHP Array
- array()
- array_change_key_case()
- array_chunk()
- array_column()
- array_combine()
- array_count_values()
- array_diff()
- array_diff_assoc()
- array_diff_key()
- array_diff_uassoc()
- array_diff_ukey()
- array_fill()
- array_fill_keys()
- array_filter()
- array_flip()
- array_intersect()
- array_intersect_assoc()
- array_intersect_key()
- array_intersect_uassoc()
- array_intersect_ukey()
- array_key_exists()
- array_keys()
- array_map()
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- array_pad()
- array_pop()
- array_product()
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- array_rand()
- array_reduce()
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- array_reverse()
- array_search()
- array_shift()
- array_slice()
- array_splice()
- array_sum()
- array_udiff()
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- array_udiff_uassoc()
- array_uintersect()
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- array_uintersect_uassoc()
- array_unique()
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- array_values()
- array_walk()
- array_walk_recursive()
- arsort()
- asort()
- compact()
- count()
- current()
- each()
- end()
- extract()
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- key()
- krsort()
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- list()
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- next()
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- PHP Calendar
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PHP Date
- PHP Date
- checkdate()
- date_add()
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- date_create()
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- date_default_timezone_set()
- date_diff()
- date_format()
- date_get_last_errors()
- date_interval_create_from_date_string()
- date_interval_format()
- date_isodate_set()
- date_modify()
- date_offset_get()
- date_parse_from_format()
- date_parse()
- date_sub()
- date_sun_info()
- date_sunrise()
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- date_time_set()
- date_timestamp_get()
- date_timestamp_set()
- date_timezone_get()
- date_timezone_set()
- date()
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- timezone_abbreviations_list()
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- timezone_open()
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- timezone_version_get()
- PHP Directory
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PHP Filesystem
- PHP Filesystem
- basename()
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- glob()
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- pclose()
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- rename()
- rewind()
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- set_file_buffer()
- stat()
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- touch()
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- PHP Filter
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PHP FTP
- PHP FTP
- ftp_alloc()
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- ftp_fput()
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- ftp_get_option()
- ftp_login()
- ftp_mdtm()
- ftp_mkdir()
- ftp_mlsd()
- ftp_nb_continue()
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- ftp_nb_fput()
- ftp_nb_get()
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- ftp_nlist()
- ftp_pasv()
- ftp_put()
- ftp_pwd()
- ftp_quit()
- ftp_raw()
- ftp_rawlist()
- ftp_rename()
- ftp_rmdir()
- ftp_set_option()
- ftp_site()
- ftp_size()
- ftp_ssl_connect()
- ftp_systype()
- PHP JSON
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PHP Keywords
- PHP Keywords
- abstract
- and
- as
- break
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- case
- catch
- class
- clone
- const
- continue
- declare
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- do
- echo
- else
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- enddeclare
- endfor
- endforeach
- endif
- endswitch
- extends
- final
- finally
- fn
- for
- foreach
- function
- global
- if
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- include
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- instanceof
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- interface
- isset
- list
- namespace
- new
- or
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- require
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- return
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- yield from
- PHP Libxml
- PHP Mail
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PHP Math
- PHP Math
- abs()
- acos()
- acosh()
- asin()
- asinh()
- atan()
- atan2()
- atanh()
- base_convert()
- bindec()
- ceil()
- cos()
- cosh()
- decbin()
- dechex()
- decoct()
- deg2rad()
- exp()
- expm1()
- floor()
- fmod()
- getrandmax()
- hexdec()
- hypot()
- intdiv()
- is_finite()
- is_infinite()
- is_nan()
- lcg_value()
- log()
- log10()
- log1p()
- max()
- min()
- mt_getrandmax()
- mt_rand()
- mt_srand()
- octdec()
- pi()
- pow()
- rad2deg()
- rand()
- round()
- sin()
- sinh()
- sqrt()
- srand()
- tan()
- tanh()
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PHP Misc
- PHP Misc
- connection_aborted()
- connection_status()
- connection_timeout()
- constant()
- define()
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- die()
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- get_browser()
- __halt_compiler()
- highlight_file()
- highlight_string()
- hrtime()
- ignore_user_abort()
- pack()
- php_strip_whitespace()
- show_source()
- sleep()
- sys_getloadavg()
- time_nanosleep()
- time_sleep_until()
- uniqid()
- unpack()
- usleep()
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PHP MySQLi
- PHP MySQLi
- affected_rows
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- info
- init
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- sqlstate
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- stat
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- use_result
- warning_count
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PHP Network
- PHP Network
- checkdnsrr()
- closelog()
- dns_check_record()
- dns_get_mx()
- dns_get_record()
- fsockopen()
- gethostbyaddr()
- gethostbyname()
- gethostbynamel()
- gethostname()
- getmxrr()
- getprotobyname()
- getprotobynumber()
- getservbyname()
- getservbyport()
- header_register_callback()
- header_remove()
- header()
- headers_list()
- headers_sent()
- http_response_code()
- inet_ntop()
- inet_pton()
- ip2long()
- long2ip()
- openlog()
- pfsockopen()
- setcookie()
- setrawcookie()
- socket_get_status()
- socket_set_blocking()
- socket_set_timeout()
- syslog()
- PHP Output Control
- PHP RegEx
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PHP SimpleXML
- PHP SimpleXML
- __construct()
- __tostring()
- addAttribute()
- addChild()
- asXML()
- attributes()
- children()
- count()
- getDocNamespaces()
- getName()
- getNamespaces()
- registerXPathNamespace()
- saveXML()
- simplexml_import_dom()
- simplexml_load_file()
- simplexml_load_string()
- xpath()
- current()
- getchildren()
- haschildren()
- key()
- next()
- rewind()
- valid()
- PHP Stream
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PHP String
- PHP String
- addcslashes()
- addslashes()
- bin2hex()
- chop()
- chr()
- chunk_split()
- convert_cyr_string()
- convert_uudecode()
- convert_uuencode()
- count_chars()
- crc32()
- crypt()
- echo()
- explode()
- fprint()
- get_html_translation_table()
- hebrev()
- hebrevc()
- hex2bin()
- html_entity_decode()
- htmlentities()
- htmlspecialchars_decode()
- htmlspecialchars()
- implode()
- join()
- lcfirst()
- levenshtein()
- localeconv()
- ltrim()
- md5()
- md5_file()
- metaphone()
- money_format()
- nl_langinfo()
- nl2br()
- number_format()
- ord()
- parse_str()
- print()
- printf()
- quoted_printable_decode()
- quoted_printable_encode()
- quotemeta()
- rtrim()
- setlocale()
- sha1()
- sha1_file()
- similar_text()
- soundex()
- sprintf()
- sscanf()
- str_getcsv()
- str_ireplace()
- str_pad()
- str_repeat()
- str_replace()
- str_rot13()
- str_shuffle()
- str_split()
- str_word_count()
- strcasecmp()
- strchr()
- strcmp()
- strcoll()
- strcspn()
- strip_tags()
- stripcslashes()
- stripslashes()
- stripos()
- stristr()
- strlen()
- strnatcasecmp()
- strnatcmp()
- strncasecmp()
- strncmp()
- strpbrk()
- strpos()
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- strripos()
- strrpos()
- strspn()
- strstr()
- strtok()
- strtolower()
- strtoupper()
- strtr()
- substr()
- substr_compare()
- substr_count()
- substr_replace()
- trim()
- ucfirst()
- ucwords()
- vfprintf()
- vprintf()
- vsprintf()
- wordwrap()
-
PHP Variable Handling
- PHP Variable Handling
- boolval()
- debug_zval_dump()
- doubleval()
- is_countable()
- empty()
- floatval()
- get_defined_vars()
- get_resource_type()
- gettype()
- intval()
- is_array()
- is_bool()
- is_callable()
- is_double()
- is_float()
- is_int()
- is_integer()
- is_iterable()
- is_long()
- is_null()
- is_numeric()
- is_object()
- is_real()
- is_resource()
- is_scalar()
- is_string()
- isset()
- print_r()
- serialize()
- settype()
- strval()
- unserialize()
- unset()
- var_dump()
- var_export()
-
PHP XML Parser
- PHP XML Parser
- utf8_decode()
- utf8_encode()
- xml_error_string()
- xml_get_current_byte_index()
- xml_get_current_column_number()
- xml_get_current_line_number()
- xml_get_error_code()
- xml_parse()
- xml_parse_into_struct()
- xml_parser_create_ns()
- xml_parser_create()
- xml_parser_free()
- xml_parser_get_option()
- xml_parser_set_option()
- xml_set_character_data_handler()
- xml_set_default_handler()
- xml_set_element_handler()
- xml_set_end_namespace_decl_handler()
- xml_set_external_entity_ref_handler()
- xml_set_notation_decl_handler()
- xml_set_object()
- xml_set_processing_instruction_handler()
- xml_set_start_namespace_decl_handler()
- xml_set_unparsed_entity_decl_handler()
- PHP Zip
- PHP Timezones
PHP if Keyword
Example
Print a string if $a is less than five:
<?php
$a = 4;
if($a < 5) {
echo "Less than five";
}
?>
Try it Yourself »
Definition and Usage
The if keyword is used to create an if conditional. The elseif and else keywords can be used to specify code that runs when the condition is not met.
Related Pages
The elseif keyword
The else keyword
Read more about conditionals in our PHP Conditionals Tutorial.
❮ PHP Keywords
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