What are the common PHP system constants?

This article introduces what the commonly used PHP system constants are, the content is very detailed, interested friends can refer to, hope to be helpful to you.

There are many things we need to learn deeply in the PHP language, and we should constantly update our knowledge base to make up for the deficiencies. PHP defines some system information and mathematical constants as system constants. These PHP system constants can be used at any time in the program, but the values of these constants cannot be changed. The system constant does not have a "$" symbol and is usually capitalized. Here are some common PHP system constants:

_ _ FILE__ current PHP file name

_ _ LINE__ the number of lines in the current PHP file

_ _ the function currently executed by FUNCTION__

_ _ the class currently executed by CLASS__

The version of PHP_VERSION PHP

PHP_OS operating system of the current server

TRUE is the same as true

FALSE is the same as false

E_ERROR to the most recent error

E_WARNING to the most recent warning

There are errors in E_PARSE syntax.

There are anomalies in E_NOTICE PHP language

M__PI pi

Scientific constant e

The logarithm of e of M__LOG2E with base 2

Logarithm of M_LOG10E with base 10

Natural logarithm of M_LN2 2

Natural logarithm of M_LN10 10

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