Some introductory knowledge of PHP

An "array" is a collection of data. Divided into: indexed arrays and associative arrays. There are three definitions of syntax: Array (), [], array name [].

Class and object: Define class: Class name; Define object: New class name (); a property or function in a class is defined with public. Access the properties or functions of an object, with a symbol.

Cast: Cast: (Type of conversion) value; automatic conversion of arrays: can only be converted to BOOL values automatically

"Arithmetic operators": + 、-、 *,/,%, $i + +: Self-increment, first execute program re-assignment, + + $i: First assign, then execute the program. Array operation: Retains the value of the previous index if the index repeats.

Connection of arrays with Array_merge ($a, $b, $c)

"Comparison operators":>, <, = =, = = =. = = = value is equal; = = = value is equal and type is the same

"Trinocular operator": syntax: conditional expression? When the condition is established, execute this code: when the condition is not established, execute this code;

"Logical operator": or (or) | | ; with (and) &&; non!. Or is it true that all is false, and that it is true that all is true for false.

"Bitwise operation": or |; with &; non-; XOR ^.

Some introductory knowledge of PHP