PHP data type automatic conversion

1: Overview---php is a weakly typed language, which can automatically convert data types according to changes in the running environment

1.1 Principles of conversion to Boolean types

　The following values ​​will be converted into Boolean types false:

　 A. Boolean type false;

　 B. Empty string ''

　 C. Positive number 0 or floating point number 0.0 or string '0' (excluding string '0.0')

　 D .Array without members----array()

　 E.null

Except for this, all other values ​​are converted to true.

1.2 Principles of conversion to numerical type

A. If the string is a legal number If the string does not contain ./e/E and does not exceed the storage range of the integer type, it will be converted to an integer type; otherwise, it will be converted to a floating point type;

　B. If the numeric string starts with an illegal character, then converted to 0;

C. Boolean true is converted to integer 1, false is converted to integer 0;

D. null is converted to 0

E. Floating point numbers are rounded down when converted to integers

1.3 Conversion The principle of converting into a string

A. The value is converted into a string, which is the value itself; String'';

　 D. Convert the array to Array

　 E. The resource will be converted to Resource id #number

The above introduces the automatic conversion of data types in PHP, including aspects of it. I hope it will be helpful to friends who are interested in PHP tutorials.