Summary of commonly used system functions in php

怪我咯
Release: 2023-03-13 06:24:02
Original
1759 people have browsed it

This article introduces the commonly used system functions in php, which has a good reference value. Let’s take a look at it with the editor

String function

strlen : Get the string length, byte length

substr: String interception, get the string (intercepted according to bytes)

strchr: Similar to substr, from Intercept at the specified position until the end

strrchr (get the file suffix name): Same as strchr, just search for characters from the right

strtolower: All characters are lowercase (for English letters)

strtoupper: All characters are uppercase

strrev: String reversal (only English can be reversed: English storage has only one byte), reversed according to bytes

strpos: Find the position where the corresponding character appears in the string (numeric subscript), start from the leftmost to find

strrpos: Same as strpos, just start from the right side of the string to find

trim : Remove the characters on both sides of the function, the default is spaces

Time and date function

time: Get the timestamp of the current time (integer: from 1970 Greenwich Mean Time Number of seconds starting at 0:00:00 on January 1st

date: Time serialization function, converts the specified timestamp into the specified time and date display format (arbitrary string: professional format Requirements), if no timestamp is specified, the system defaults to the timestamp of the current time

strtotime: A string in the time and date format is converted into the corresponding timestamp (as long as it is a correct English time expression, any Convert)

microtime: microsecond timestamp, returns different results according to different requirements Mixed microtime (Boolean type), can return a floating point number of time, or can return an array (timestamp and microseconds Number)

Mathematical related functions

abs: absolute value

floor: round down floor(3.2) The result is equal to 3

ceil: Round up

round: Round off

rand: Get a random integer within the specified range

mt_rand: Get a random integer within the specified range (efficiency Higher)

Array related functions

key: Get the subscript of the element pointed to by the current pointer of the current array

current: Get the current pointer The value pointing to the element

next: Get the value of the next element and move the pointer down

prev: Get the value of the previous element and move the pointer up

end: Move the pointer to the last element of the array and return the value of the final pointer position

reset: Move the pointer to the first element of the array and return the value of the final pointer position

array_keys: Get all the key names of an array, return an index array

array_values: Get all the values ​​of an array, return an index array

explode: Explode, will A string divides the array into multiple segments according to a specified rule (usually special characters). Each segment is treated as an element of the array and an index array is returned.

implode: Glue, combine an array All elements inside are spliced ​​into a string according to a specified rule (special characters)

array_merge: Merge refers to accumulating the elements in two arrays. If the subsequent array has the same subscript (key name: association) as the previous array, then the value of the subsequent element will overwrite the previous one; if it is the same subscript of the index, the subscript will be automatically modified and superimposed on the previous array. inside.

Data structure simulation function

array_shift: Pop elements from the front of the array and get the value of the element

array_pop: Pop elements from the back of the array, Get the value of the element

array_unshift: Push elements from the front of the array to get the number of current array elements

array_push: Push elements from the back of the array to get The number of current array elements

Determine the variable

is_bool: Determine whether it is a Boolean type

is_float: Determine the floating point type

is_integer:Judge integer type

is_object:Judge object

is_array:Judge array

is_string:Judge string

is_resource:Judge resource

is_scalar: scalar is scalar, the judgment is basic Data type: integer, floating point, Boolean and string type

is_null: whether it is empty

is_numeric: Determine numbers or strings composed of pure numbers

gettype: get the data type

settype: change the data type

File operation function

opendir (path): Open a path resource (read all data inside the path into memory)

readdir (path resource): Read the current resource pointer from the folder resource The name of the pointed file, the pointer will move downward one bit

closedir (resource): release the corresponding file resource

scandir (path): read all file names inside a path, Returns an array, each element of the array is a file name.

file_exists: Determine whether a file exists (file is a broad sense: path and file)

is_dir: Determine whether a specified path exists (folder)

is_file: Determine whether a specified path is a file (file)

mkdir: Create a path, if the path exists Error

rmdir: Remove folder

file_get_contents: Read data content from a specified file.

file_put_contents: Write the specified string to the corresponding file

fopen: Open a file resource

fgetc: c represents character, once Read a character

fgets: s represents string, which means multiple characters can be read, depending on the specified read length or whether a newline is encountered (only one line of data can be read at most)

Both functions operate on the current resource pointer, and will move the pointer down after reading.

fread: Get the specified length of data until the end of the file

fwrite: To the file resource pointer Write data to the position. Writing will not move the existing things back at the current position, but will overwrite them.

fseek: Specify the pointer to the corresponding position

fclose: Use the corresponding File resources

copy: copy

unlink: delete file

rename: rename file

filemtime: m represents modify, the file was last modified Time

filesize: File size (bytes)

fileperms: File permissions (octal under Linux)

The above is the detailed content of Summary of commonly used system functions in php. For more information, please follow other related articles on the PHP Chinese website!

Related labels:
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn:Public welfare online PHP training,Help PHP learners grow quickly!