


A brief discussion on PHP forced type conversion, use with caution!_PHP Tutorial
PHP is a weakly typed language. This is its advantage and feature, but sometimes you have to convert the type accordingly.
The problem comes at this time. Because in many cases, you will find that the data obtained after converting the type is quite different from the expected value.
Here I use forced conversion to integer as an example.
Looking at the code below, it can be said that it is absolutely impossible for you to tell the correct answer.
echo (int) 123.99999999999999;
echo (int) -1.999999999999999;
echo (int) -1.9999999999999999; 9999999999999;
echo (int) - 10.999999999999999;
echo (int) -1000.9999999999999;
echo (int) -9999999999;
First of all, I want to explain my system environment. win7 X86
The results obtained are as follows124
-1
-2
-1
-10
-1001
-1410065407
The official statement is:
When converting from a floating point number to an integer, it will be rounded towards zero.
If the floating point number is outside the integer range (usually +/- 2.15e+9 = 2^31), the result is undefined because there is not enough precision to make the float Points gives an exact integer result. There is no warning in this case, not even any notification!
Seeing this, you may think that the example I gave above is a bit far-fetched. Because it is simply impossible to use such high precision.
So, let’s look at the example below.
echo (int) ( (0.1+0.7) * 10 );
No need to guess, the execution result here is---7!Yes, you read it correctly and I typed it correctly. The result is 7 , not 8 as we usually think.
Now, you know how fucked up PHP is!
PHP official has this warning:
Never cast an unknown fraction to an integer, as this can sometimes lead to unpredictable results.
So be careful when performing forced type conversion! Large numerical values, high precision, and fractions should be used with caution!Of course, the above example can be handled this way.
x$num = (0.1 + 0.7) * 10;
echo (int) $num;

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 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 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.

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 and Python each have their own advantages, and the choice should be based on project requirements. 1.PHP is suitable for web development, with simple syntax and high execution efficiency. 2. Python is suitable for data science and machine learning, with concise syntax and rich libraries.

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP is suitable for web development, especially in rapid development and processing dynamic content, but is not good at data science and enterprise-level applications. Compared with Python, PHP has more advantages in web development, but is not as good as Python in the field of data science; compared with Java, PHP performs worse in enterprise-level applications, but is more flexible in web development; compared with JavaScript, PHP is more concise in back-end development, but is not as good as JavaScript in front-end development.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.
