PHP 8.4

array_replace() - Replaces elements from passed arrays into one array.
array_replace_recursive() - Recursively replaces elements from passed arrays into one array.
class_alias() - Creates an alias for a user defined class.
forward_static_call() - Call a user function from a method context.
forward_static_call_array() - Call a user function from a method context, with the arguments contained in an array.
gc_collect_cycles() - Forces collection of any existing garbage cycles.
gc_disable() - Deactivates the circular reference collector.
gc_enable() - Activates the circular reference collector.
gc_enabled() - Returns the status of the circular reference collector.
get_called_class() - Return the name of the class a static method is called in.
gethostname() - Return the current host name for the local machine.
header_remove() - Removes an HTTP header previously set using the header() function.
lcfirst() - Make a string's first character lowercase.
parse_ini_string() - Parse a configuration string.
quoted_printable_encode() - Convert an 8 bit string to a quoted-printable string.
str_getcsv() - Parse a CSV string into an array.
stream_context_set_default() - Set the default stream context.
stream_supports_lock() - Return TRUE if the stream supports locking.
stream_context_get_params() - Retrieve parameters from a stream context.
streamWrapper::stream_cast() - Retrieve the underlying stream resource.
streamWrapper::stream_set_option() - Change stream options

Date/Time:

date_add() - Adds an amount of days, months, years, hours, minutes and seconds to a DateTime object.
date_create_from_format() - Returns a new DateTime object formatted according to the given format.
date_diff() - Returns the difference between two DateTime objects.
date_get_last_errors() - Returns the warnings and errors from the last date/time operation.
date_parse_from_format() - Get information about a given date.
date_sub() - Subtracts an amount of days, months, years, hours, minutes and seconds from a DateTime object.
timezone_version_get() - Returns the version of the timezonedb.

GMP:

gmp_testbit() - Tests whether a bit is set.

Hash:

hash_copy() - Copy hashing context.

IMAP:

imap_gc() - Clears IMAP cache.
imap_utf8_to_mutf7() - Encode a UTF-8 string to modified UTF-7.
imap_mutf7_to_utf8() - Decode a modified UTF-7 string to UTF-8.

JSON:

json_last_error() - Returns the last JSON error that occurred.

MySQL Improved:

mysqli_fetch_all() - Fetches all result rows as an associative array, a numeric array, or both.
mysqli_get_connection_stats() - Returns statistics about the client connection.
mysqli_poll() - Poll connections.
mysqli_reap_async_query() - Get result from async query.

OpenSSL:

openssl_random_pseudo_bytes() - Returns a string of the given length specified, filled with pseudo-random bytes.

PCNTL:

pcntl_signal_dispatch() - Calls signal handlers for pending signals.
pcntl_sigprocmask() - Sets and retrieves blocked signals.
pcntl_sigtimedwait() - Wait for signals with a timeout.
pcntl_sigwaitinfo() - Wait for signals.

PCRE:

preg_filter() - Perform a regular expression search and replace, returning only results which matched the pattern.

Semaphore:

msg_queue_exists() - Check whether a message queue exists.
shm_has_var() - Checks whether a specific key exists inside a shared memory segment.

The following functions are now natively implemented, making them available on all operating systems which can run PHP:

PHP 5.2

New Functions

PHP 5.2.x introduced some new functions:

PHP Core:

array_fill_keys() - Create an array using the elements of the first parameter as keys, each initialized to val
error_get_last() - Get the last occurred error as associative array. Returns NULL if there hasn't been an error yet
image_type_to_extension() - Get file extension for image-type returned by getimagesize(), exif_read_data(), exif_thumbnail(), exif_imagetype()
memory_get_peak_usage() - Returns the peak allocated by PHP memory
sys_get_temp_dir() - Returns directory path used for temporary files. (Added in 5.2.1)
timezone_abbreviations_list() - Returns associative array containing DST, offset and the timezone name
timezone_identifiers_list() - Returns numerically indexed array with all timezone identifiers
timezone_name_from_abbr() - Returns the timezone name from abbreviation
stream_socket_shutdown() - Causes all or part of a full-duplex connection on the socket associated with stream to be shut down. As of PHP 5.2.1.

Image:

imagegrabscreen() - Grabs a screenshot of the whole screen. As of PHP 5.2.2.
imagegrabwindow() - Captures a window. As of PHP 5.2.2.

libXML:

libxml_disable_entity_loader() - Disable the ability to load external entities. As of PHP 5.2.11.

mbstring:

mb_stripos() - Finds position of first occurrence of a string within another, case insensitive
mb_stristr() - Finds first occurrence of a string within another, case insensitive
mb_strrchr() - Finds the last occurrence of a character in a string within another
mb_strrichr() - Finds the last occurrence of a character in a string within another, case insensitive
mb_strripos() - Finds position of last occurrence of a string within another, case insensitive
mb_strstr() - Finds first occurrence of a string within another

ming (As of PHP 5.2.1):

void ming_setSWFCompression(int num) - Sets output compression
void swfmovie::namedanchor(string name) - Creates anchor
void swfmovie::protect([string password]) - Protects

openssl:

openssl_csr_get_public_key() - Extracts public key from a CERT and prepares it for use
openssl_csr_get_subject() - Returns the subject of a CERT
openssl_pkey_get_details() - Returns an array with the key details (bits, pkey, type)

spl:

spl_object_hash() - Return hash id for given object
int iterator_apply(Traversable it, mixed function [, mixed params]) - Calls a function for every element in an iterator

pcre:

preg_last_error() - Returns the error code of the last regex execution

pgsql:

pg_field_table() - Returns the name of the table field belongs to, or table's oid if oid_only is TRUE

posix:

posix_initgroups() - Calculate the group access list for the user specified in name

gmp:

gmp_nextprime() - Finds next prime number

xmlwriter:

xmlwriter_full_end_element() - End current element - returns FALSE on error
xmlwriter_write_raw() - Write text - returns FALSE on error
xmlwriter_start_dtd_entity() - Create start DTD Entity - returns FALSE on error
xmlwriter_end_dtd_entity() - End current DTD Entity - returns FALSE on error
xmlwriter_write_dtd_entity() - Write full DTD Entity tag - returns FALSE on error

PHP 5.0

New Functions

In PHP 5 there are some new functions. Here is the list of them:

Arrays:

array_combine() - Creates an array by using one array for keys and another for its values
array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
array_udiff() - Computes the difference of arrays by using a callback function for data comparison
array_udiff_assoc() - Computes the difference of arrays with additional index check. The data is compared by using a callback function
array_udiff_uassoc() - Computes the difference of arrays with additional index check. The data is compared by using a callback function. The index check is done by a callback function also
array_walk_recursive() - Apply a user function recursively to every member of an array
array_uintersect_assoc() - Computes the intersection of arrays with additional index check. The data is compared by using a callback function
array_uintersect_uassoc() - Computes the intersection of arrays with additional index check. Both the data and the indexes are compared by using separate callback functions
array_uintersect() - Computes the intersection of arrays. The data is compared by using a callback function

InterBase:

ibase_affected_rows() - Return the number of rows that were affected by the previous query
ibase_backup() - Initiates a backup task in the service manager and returns immediately
ibase_commit_ret() - Commit a transaction without closing it
ibase_db_info() - Request statistics about a database
ibase_drop_db() - Drops a database
ibase_errcode() - Return an error code
ibase_free_event_handler() - Cancels a registered event handler
ibase_gen_id() - Increments the named generator and returns its new value
ibase_maintain_db() - Execute a maintenance command on the database server
ibase_name_result() - Assigns a name to a result set
ibase_num_params() - Return the number of parameters in a prepared query
ibase_param_info() - Return information about a parameter in a prepared query
ibase_restore() - Initiates a restore task in the service manager and returns immediately
ibase_rollback_ret() - Rollback transaction and retain the transaction context
ibase_server_info() - Request statistics about a database server
ibase_service_attach() - Connect to the service manager
ibase_service_detach() - Disconnect from the service manager
ibase_set_event_handler() - Register a callback function to be called when events are posted
ibase_wait_event() - Wait for an event to be posted by the database

iconv:

iconv_mime_decode() - Decodes a MIME header field
iconv_mime_decode_headers() - Decodes multiple MIME header fields at once
iconv_mime_encode() - Composes a MIME header field
iconv_strlen() - Returns the character count of string
iconv_strpos() - Finds position of first occurrence of a needle within a haystack
iconv_strrpos() - Finds the last occurrence of a needle within a haystack
iconv_substr() - Cut out part of a string

Streams:

stream_copy_to_stream() - Copies data from one stream to another
stream_get_line() - Gets line from stream resource up to a given delimiter
stream_socket_accept() - Accept a connection on a socket created by stream_socket_server()
stream_socket_client() - Open Internet or Unix domain socket connection
stream_socket_get_name() - Retrieve the name of the local or remote sockets
stream_socket_recvfrom() - Receives data from a socket, connected or not
stream_socket_sendto() - Sends a message to a socket, whether it is connected or not
stream_socket_server() - Create an Internet or Unix domain server socket

Date and time related:

idate() - Format a local time/date as integer
date_sunset() - Time of sunset for a given day and location
date_sunrise() - Time of sunrise for a given day and location
time_nanosleep() - Delay for a number of seconds and nanoseconds

Strings:

str_split() - Convert a string to an array
strpbrk() - Search a string for any of a set of characters
substr_compare() - Binary safe optionally case insensitive comparison of two strings from an offset, up to length characters

Other:

convert_uudecode() - decode a uuencoded string
convert_uuencode() - uuencode a string
curl_copy_handle() - Copy a cURL handle along with all of its preferences
dba_key_split() - Splits a key in string representation into array representation
dbase_get_header_info() - Get the header info of a dBase database
dbx_fetch_row() - Fetches rows from a query-result that had the DBX_RESULT_UNBUFFERED flag set
fbsql_set_password() - Change the password for a given user
file_put_contents() - Write a string to a file
ftp_alloc() - Allocates space for a file to be uploaded
get_declared_interfaces() - Returns an array of all declared interfaces
get_headers() - Fetches all the headers sent by the server in response to a HTTP request
headers_list() - Returns a list of response headers sent (or ready to send)
http_build_query() - Generate URL-encoded query string
image_type_to_extension() - Get file extension for image-type returned by getimagesize(), exif_read_data(), exif_thumbnail(), exif_imagetype()
imagefilter() - Applies a filter to an image using custom arguments
imap_getacl() - Gets the ACL for a given mailbox
ldap_sasl_bind() - Bind to LDAP directory using SASL
mb_list_encodings() - Returns an array of all supported encodings
pcntl_getpriority() - Get the priority of any process
pcntl_wait() - Waits on or returns the status of a forked child as defined by the waitpid() system call
pg_version() - Returns an array with client, protocol and server version (when available)
php_check_syntax() - Check the syntax of the specified file
php_strip_whitespace() - Return source with stripped comments and whitespace
proc_nice() - Change the priority of the current process
pspell_config_data_dir() - Change location of language data files
pspell_config_dict_dir() - Change location of the main word list
setrawcookie() - Send a cookie without URL-encoding the value
scandir() - List files and directories inside the specified path
snmp_read_mib() - Reads and parses a MIB file into the active MIB tree
sqlite_fetch_column_types() - Return an array of column types from a particular table

Note:
The Tidy extension has also changed its API completely.