php predefined functions


Functions are blocks of codes that perform specific task in php. It makes the codes reusable and shorthand. it can be categorized into two groups.

Predefined functions are the inbuilt functions of php. These functions can be subdivided into multiple categories as stated below.

string functions

numeric functions

date and time functions

array functions

directory functions

String Function

strtolower(); -> converts all characters of the string to lower case

strtoupper(); -> converts all characters of the string to upper case

ucfirst(); -> converts first letter to upper case

ucwords(); -> converts first letter of each word to upper case

strlen(); -> counts number of characters in a string and returns integer value

trim(); -> trims unnecessary spaces

ltrim(); -> trims unnecessary spaces from left

rtrim(); -> trims unnecessary spaces from right

sprintf("%s,%s,%s",$a,$b,$c); -> placeholder to keep the value

str_word_count() -> count the number of words

$count = str_word_count($x,1) -> returns array

strstr(); echo strstr($str,U,true);

stristr(); case insensitive strstr

str_replace() -> search and replace characters from the string

str_repeat() -> repeats the string

substr(int,int) -> prints a string from defined initial character number to defined last number

strpos() -> finds position of the string

Numeric Function

abs() -> returns positive value of a number

sqrt() -> returns square root of a number

round() -> rounds a floating number

floor() -> rounds a number down to a nearest integer

ceil() -> rounds a number up to a nearest integer

rand() -> generates a random integer

mt_rand() -> generates random number between defined inital and end number

pow() -> returns x raised to the power of y

pi() -> returns the value of pi

min() -> returns the lowest value from an array

max() -> returns the highest value from an array

fmod() -> returns the remainder from x/y {%}

bindec() -> converts a binary number to a decimal number

decbin() -> converts a decimal number to a binary number

deg2rad() -> converts a degree value to a radian value

rad2deg() -> converts a radian value to a degree value

Array Functions

array() -> creates an array

sizeof() -> counts the number of values in an array

sort() -> sorts an indexed array in ascending order

in_array() -> checks if a specified value is in array

list() -> keep array values in variable

compact() -> keeps variable values in associative array

arsort() -> sorts an associative array in descending order according to the value

array_unique() -> removes duplicate values from an array

explode() -> converts string to array

implode() -> converts array to string

extract() -> converts array to variable

array_sum() -> returns the sum of values in an array

array_shift() -> removes the first element of an array and returns the first value from the array

array_pop() -> deletes the last element from an array

array_merge() -> merges multiple arrays

array_search() -> searches for a defined value in an array and returns the key for that value

array_reverse() -> returns an array in reverse order

array_keys() -> returns all the keys from an array

Directory Functions

getcwd() -> get current working directory

mkdir() -> make directory

rmdir() -> remove directory

dirname() -> directory name

__DIR__ -> directory name

__FILE__ -> filename along with directory

__LINE__ -> line number

file_exists() -> checks if file exists and returns boolean value

unlink() -> remove file

is_file() -> boolean

is_dir() -> boolean

scan_dir() -> returns array of files present in the directory

file_size() -> returns file size in bytes

filectime() -> file created time (timestamps)

pathinfo() -> returns array / string based on arguments

copy() -> copy file