


Teach you how to use string functions to insert backslashes before characters
Today we will introduce a new chapter, string functions. String functions are part of the PHP core and no installation is required to use these functions. Today we will introduce it.
Old rules, first let’s talk about what a string function is.
String functions, also known as string processing functions, refer to functions used for string processing in programming languages, such as string copying, length calculation, character search, etc., which can be used in C, Functions used in Pascal, visual and LotusScript.
After we understand what string functions are, let's start today's topic, inserting a backslash before the character.
In fact, there are two ways to insert a backslash before a character. There is a little difference between the two methods. Let's look at the first one first.
The first, addcslashes() function
Let’s look at a small example first.
<?php $str = addcslashes("Hello World!","W"); echo($str); ?>
The result is
Hello \World!
As can be seen from this example, we add "\" in front of "w", and this w is also specified externally, So the addcslashes() function can insert a backslash before the specified character.
Let’s see if that’s right, yes it is. The addcslashes() function returns a string with a backslash added before the specified character.
It should be noted that the addcslashes() function is case sensitive
. Be careful when applying addcslashes() to 0 (NULL), r (carriage return), n (line feed), t (form feed), f (tab), and v (vertical tab). In PHP, \0, \r, \n, \t, \f and \v are predefined escape sequences.
Now that the first method has been introduced, let’s take a look at the second method to see what the difference is between this method and the previous one.
Second type, addslashes() function
Let’s look at a small example.
<?php $str = addslashes('What does "yolo" mean?'); echo($str); ?>
The result is
What does \"yolo\" mean?
This example is different from the previous example. It does not specify characters, but adds a backslash in front of some characters. It is so magical. What's going on? We take a closer look at the code and find that there is a double quote after the backslash. Is this the reason? Let's take a look at the answer.
addslashes() function returns a string with a backslash added before predefined characters, and this function can be used to prepare appropriate strings for strings stored in the database and database query statements.
The predefined characters are:
Single quotation mark (')
Double quotation mark (")
Backslash (\)
NULL
magic_quotes_gpc is on, automatically runs
addslashes() for all
GET,
POST and
COOKIE data. Do not Use addslashes() for strings that have been escaped by magic_quotes_gpc, because this will cause double-level escaping. When encountering this situation, you can use the function
get_magic_quotes_gpc() for detection.
The above is the detailed content of Teach you how to use string functions to insert backslashes before characters. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

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

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

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,

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

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

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.

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.
