##PHP Array Functions
array_diff (arr1, arr2 ...)
array_filter (arr, function)
array_flip (arr)
array_intersect (arr1, arr2 ...)
array_merge (arr1, arr2 ...)
array_pop (arr)
array_push (arr, var1, var2 ...)
array_reverse (arr)
array_search (needle, arr)
array_walk (arr, function)
count (count)
in_array (needle, haystack)
##PHP String Functions
crypt (str, salt)
explode (sep, str)
implode (glue, arr)
nl2br (str)
sprintf (frmt, args)
strip_tags (str, allowed_tags)
str_replace (search, replace, str)
strpos (str, needle)
strrev (str)
strstr (str, needle)
strtolower (str)
strtoupper (str)
substr (string, start, len)
##PHP Filesystem Functions
clearstatcache ()
copy (source, dest)
fclose (handle)
fgets (handle, len)
file (file)
filemtime (file)
filesize (file)
file_exists (file)
fopen (file, mode)
fread (handle, len)
fwrite (handle, str)
readfile (file)
##PHP Date and Time Functions
checkdate (month, day, year)
date (format, timestamp)
getdate (timestamp)
mktime (hr, min, sec, month, day, yr)
strftime (formatstring, timestamp)
strtotime (str)
time ()
##PHP Regular Expressions Functions
ereg (pattern, str)
split (pattern, str)
ereg_replace (pattern, replace, str)
preg_grep (pattern, arr)
preg_match (pattern, str)
preg_match_all (pattern, str, arr)
preg_replace (pattern, replace, str)
preg_split (pattern, str)
##Regular Expressions Syntax
| characters | description |
|---|---|
| ^ | Start of string |
| $ | End of string |
| . | Any single character |
| (a|b) | a or b |
| (...) | Group section |
| [abc] | In range (a, b or c) |
| [^abc] | Not in range |
| \s | White space |
| a? | Zero or one of a |
| a* | Zero or more of a |
| a*? | Zero or more, ungreedy |
| a+ | One or more of a |
| a+? | One or more, ungreedy |
| a{3} | Exactly 3 of a |
| a{3,} | 3 or more of a |
| a{,6} | Up to 6 of a |
| a{3,6} | 3 to 6 of a |
| a{3,6}? | 3 to 6 of a, ungreedy |
| |Escape character | |
| [:punct:] | Any punctuation symbol |
| [:space:] | Any space character |
| [:blank:] | Space or tab |
##Pattern Modifiers
| character | description |
|---|---|
| g | Global match |
| i * | Case-insensitive |
| m * | Multiple lines |
| s * | Treat string as single line |
| x * | Allow comments and whitespace in pattern |
| e * | Evaluate replacement |
| U * | Ungreedy pattern |
| * PCRE modifier |
##PHP fopen() Modes
| character | description |
|---|---|
| r | Read |
| r+ | Read and write, prepend |
| w | Write, truncate |
| w+ | Read and write, truncate |
| a | Write, append |
| a+ | Read and write, append |
##PHP Date Formatting
| character | description |
|---|---|
| Y | 4 digit year (2008) |
| y | 2 digit year (08) |
| F | Long month (January) |
| M | Short month (Jan) |
| m | Month ⁴ (01 to 12) |
| n | Month (1 to 12) |
| D | Short day name (Mon) |
| l | Long day name (Monday) (lowercase L) |
| d | Day ⁴ (01 to 31) |
| j | Day (1 to 31) |
| h|12 Hour ⁴ (01 to 12) g|12 Hour (1 to 12) H|24 Hour ⁴ (00 to 23) G|24 Hour (0 to 23) i|Minutes ⁴ (00 to 59) s|Seconds ⁴ (00 to 59) | w|Day of week ¹ (0 to 6) z|Day of year (0 to 365) W|Week of year ² (1 to 53) t|Days in month (28 to 31) | a|am or pm A|AM or PM B|Swatch Internet Time (000 to 999) S|Ordinal Suffix (st, nd, rd, th) | T|Timezone of machine (GMT) Z|Timezone offset (seconds) O|GMT offset (hours) (+0200) I|Daylight saving (1 or 0) L|Leap year (1 or 0) | U|Seconds since Epoch ³ c|ISO 8601 (PHP 5) (2008-07-31T18:30:13+01:00) r|RFC 2822 (Thu, 31 Jul 2008 18:30:13 +0100)
- ¹ 0 is Sunday, 6 is Saturday.
- ² Week that overlaps two years belongs to year that contains most days of that week. Hence week number for 1st January of a given year can be 53 if week belongs to previous year. date("W", mktime(0, 0, 0, 12, 8, $year)) always gives correct number of weeks in $year.
- ³ The Epoch is the 1st January 1970.
- ⁴ With leading zeroes
##Comparisons of $x with PHP functions
| Expression | gettype() | empty() | is_null() | isset() | boolean : if($x) |
|---|---|---|---|---|---|
| $x = ""; | string | TRUE | FALSE | TRUE | FALSE |
| $x = null; | NULL | TRUE | TRUE | FALSE | FALSE |
| var $x; | NULL | TRUE | TRUE | FALSE | FALSE |
| $x is undefined | NULL | TRUE | TRUE | FALSE | FALSE |
| $x = array(); | array | TRUE | FALSE | TRUE | FALSE |
| $x = array('a', 'b'); | array | FALSE | FALSE | TRUE | TRUE |
| $x = false; | boolean | TRUE | FALSE | TRUE | FALSE |
| $x = true; | boolean | FALSE | FALSE | TRUE | TRUE |
| $x = 1; | integer | FALSE | FALSE | TRUE | TRUE |
| $x = 42; | integer | FALSE | FALSE | TRUE | TRUE |
| $x = 0; | integer | TRUE | FALSE | TRUE | FALSE |
| $x = -1; | integer | FALSE | FALSE | TRUE | TRUE |
| $x = "1"; | string | FALSE | FALSE | TRUE | TRUE |
| $x = "0"; | string | TRUE | FALSE | TRUE | FALSE |
| $x = "-1"; | string | FALSE | FALSE | TRUE | TRUE |
| $x = "php"; | string | FALSE | FALSE | TRUE | TRUE |
| $x = "true"; | string | FALSE | FALSE | TRUE | TRUE |
| $x = "false"; | string | FALSE | FALSE | TRUE | TRUE |
##Loose comparisons with == |TRUE|FALSE|1|0|-1|"1"|"0"|"-1"|NULL|array()|"php"|"" -----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|----- TRUE|TRUE|FALSE|TRUE|FALSE|TRUE|TRUE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE FALSE|FALSE|TRUE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE|TRUE|TRUE|FALSE|TRUE 1|TRUE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE 0|FALSE|TRUE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE|TRUE|FALSE|TRUE|TRUE -1|TRUE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE "1"|TRUE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE "0"|FALSE|TRUE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE "-1"|TRUE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE NULL|FALSE|TRUE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|TRUE|TRUE|FALSE|TRUE array()|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|TRUE|FALSE|FALSE "php"|TRUE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE ""|FALSE|TRUE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|TRUE
##Strict comparisons with === |TRUE|FALSE|1|0|-1|"1"|"0"|"-1"|NULL|array()|"php"|"" -----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|----- TRUE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE 1|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE 0|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE -1|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE "1"|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE "0"|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE|FALSE "-1"|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE|FALSE NULL|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE|FALSE array()|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE|FALSE "php"|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE|FALSE ""|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|FALSE|TRUE
##Comparison Operators
| Example | Name | Result |
|---|---|---|
| $a == $b | Equal | TRUE if $a is equal to $b after type juggling. |
| $a === $b | Identical | TRUE if $a is equal to $b, and they are of the same type. |
| $a != $b | Not equal | TRUE if $a is not equal to $b after type juggling. |
| $a <> $b | Not equal | TRUE if $a is not equal to $b after type juggling. |
| $a !== $b | Not identical | TRUE if $a is not equal to $b, or they are not of the same type. |
| $a < $b | Less than | TRUE if $a is strictly less than $b. |
| $a > $b | Greater than | TRUE if $a is strictly greater than $b. |
| $a <= $b | Less than or equal to | TRUE if $a is less than or equal to $b. |
| $a >= $b | Greater than or equal to | TRUE if $a is greater than or equal to $b. |
| $a <=> $b | Spaceship | An integer less than, equal to, or greater than zero when $a is respectively less than, equal to, or greater than $b. Available as of PHP 7. |
| $a ?? $b ?? $c | Null coalescing | The first operand from left to right that exists and is not NULL. NULL if no values are defined and not NULL. Available as of PHP 7. |