Home Backend Development PHP Tutorial A simple summary of learning PHP functions_PHP tutorial

A simple summary of learning PHP functions_PHP tutorial

Jul 21, 2016 pm 03:36 PM
exists file php string function exist study document examine Table of contents Simple illustrate

file_exists() Check whether the file or directory exists |
Description |
bool file_exists ( string filename ) |
Returns TRUE if the file or directory specified by filename exists, otherwise returns FALSE.

dirname() function returns the directory portion of the path.
Syntax
dirname(path) path required. Specifies the path to be checked.
Example
echo dirname("c:/testweb/home.php");
echo dirname("/testweb/home.php");
?> ;
Output
c:/testweb
/testweb
You can often see
dirname(__FILE__) in the program; What you get is the directory name of the layer where the file is located. The path of
__FILE__ is The file where the current code is located

preg_split splits the string according to the specified rules.
Syntax: array preg_split(string pattern, string subject, int [limit]);
Return value: array
This function can separate strings according to specified rules. The return value after cutting is an array variable. The parameter pattern is the specified rule string, the parameter subject is the string to be processed, and the parameter limit can be omitted, indicating the maximum number of consistent values ​​to be processed.

implode() function combines array elements into a string
Syntax
implode(separator,array)
separator optional. Specifies what is placed between array elements. Default is "" (empty string).
array required. Arrays to be combined into strings.

The file() function reads the entire file into an array.
Similar to file_get_contents(), except that file() returns the file as an array. Each cell in the array is a corresponding line in the file, including newlines.
Returns false if failed.
Syntax
file(path,include_path,context)
path required. Specifies the file to be read.
include_path optional. If you also want to search for files in include_path, you can set this parameter to "1".
context optional. Specifies the environment for a file handle.
Context is a set of options that can modify the behavior of the stream. If null is used, it is ignored.

The file_get_contents() function reads the entire file into a string.
Syntax
file_get_contents(path,include_path,context,start,max_length)
path required. Specifies the file to be read.
include_path optional. If you also want to search for files in include_path, you can set this parameter to "1".
context optional. Specifies the environment for a file handle.
Context is a set of options that can modify the behavior of the stream. If null is used, it is ignored.
start optional. Specifies the position in the file to begin reading. This parameter is new in PHP 5.1.
max_length optional. Specifies the number of bytes to read. This parameter is new in PHP 5.1.

ereg() function string comparison analysis. Case sensitive
This function uses pattern rules to parse and compare string strings. The value returned by the comparison result is placed in the array parameter regs. The content of regs[0] is the original string, regs[1] is the first string that conforms to the rules, and regs[2] is the second string that conforms to the rules. string, and so on. If the parameter regs is omitted, it will simply be compared, and the return value will be true if found.

eregi() function string comparison analysis, regardless of case.
Syntax: int eregi(string pattern, string string, array [regs]);
Used the same as ereg(), except that ereg() is case-sensitive.

str_replace() The function replaces a string with other characters in a string.
Syntax
str_replace(find,replace,string,count)
find required. Specifies the value to be found.
replace required. Specifies the value to replace the value in find.
string required. Specifies the string to be searched for.
count optional. A variable counting the number of substitutions.
Note: This function is case sensitive. Please use str_ireplace() to perform a case-insensitive search.

preg_match() function
Search the subject string for a match to the regular expression given by pattern.
If matches is provided, it will be populated with the results of the search. $matches[0] will contain text that matches the entire pattern, $matches[1] will contain text that matches the first captured subpattern in parentheses, and so on.

preg_match_all() function string overall comparison analysis.
Syntax: int preg_match_all(string pattern, string subject, array matches, int [order]);
This function uses pattern rules to parse and compare the string subject as a whole. The value returned by the comparison result is placed in the array parameter matches and sorted by the sequence value order. There are two values ​​of parameter order: PREG_PATTERN_ORDER and PREG_SET_ORDER. If there is no order value, the system automatically substitutes PREG_PATTERN_ORDER into the order value. The return value is the number of matching results. If there is no matching result or error, a false value is returned.

strcasecmp() function compares two strings.
The function returns:
0 - if the two strings are equal
<0 - if string1 is less than string2
>0 - if string1 is greater than string2
Syntax
strcasecmp(string1 ,string2)
string1 required. Specifies the first string to compare.
string2 required. Specifies the second string to be compared.

www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/322075.htmlTechArticlefile_exists() Check whether the file or directory exists bool file_exists (string filename) If the file or directory specified by filename Returns TRUE if it exists, otherwise returns FALSE. d...
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

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial
1657
14
PHP Tutorial
1257
29
C# Tutorial
1229
24
How do you parse and process HTML/XML in PHP? How do you parse and process HTML/XML in PHP? Feb 07, 2025 am 11:57 AM

This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an

Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Apr 05, 2025 am 12:04 AM

JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,

Explain late static binding in PHP (static::). Explain late static binding in PHP (static::). Apr 03, 2025 am 12:04 AM

Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.

PHP Program to Count Vowels in a String PHP Program to Count Vowels in a String Feb 07, 2025 pm 12:12 PM

A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total

What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? Apr 03, 2025 am 12:03 AM

What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.

PHP and Python: Comparing Two Popular Programming Languages PHP and Python: Comparing Two Popular Programming Languages Apr 14, 2025 am 12:13 AM

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

PHP: A Key Language for Web Development PHP: A Key Language for Web Development Apr 13, 2025 am 12:08 AM

PHP is a scripting language widely used on the server side, especially suitable for web development. 1.PHP can embed HTML, process HTTP requests and responses, and supports a variety of databases. 2.PHP is used to generate dynamic web content, process form data, access databases, etc., with strong community support and open source resources. 3. PHP is an interpreted language, and the execution process includes lexical analysis, grammatical analysis, compilation and execution. 4.PHP can be combined with MySQL for advanced applications such as user registration systems. 5. When debugging PHP, you can use functions such as error_reporting() and var_dump(). 6. Optimize PHP code to use caching mechanisms, optimize database queries and use built-in functions. 7

PHP in Action: Real-World Examples and Applications PHP in Action: Real-World Examples and Applications Apr 14, 2025 am 12:19 AM

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

See all articles