Some special syntax for PHP, useful functions, etc.

1: Do not appear?> in a single comment
2:boolean type, integer type, float/double type, string type, array type, object Type (object), resource type resource, NULL type
3: The variable between the double quotes "resolves" (Can be \$ with the escape character), the single quotation marks are not parsed, the output is as-is
4: Escape character: \ n line break \ r/T tab \ back slash \$ \ ' \ '
5: Defining the symbol <<<
For example $a = &LT;&LT;&LT;STD
adfsdfsdfsdfsdfsd\$
Std
This effect is the same as double quotes. The included variables are also converted to values.
6: Almost all programming languages = = = = = = = = = = = = = = = = = Remember.
7:is_null ($a) is series functions (Is_bool,is_string,is_int,is_integer,is_float,is_double,is_array,is_object,is_numeric)
The 8:unset variable becomes null and does not return a value.
9: Data type conversion (type) $var Boolean string,integer,float Array object can also be converted to bool Settype ($var, $type) by the Settype function
10:define (' abc ', 123); Define constant defined (' ABC ') Usage: ABC, or constant (' abc ') or $a = ' abc ' constant ($a) all capitalized
One: $a = & $b; reference assignment
12: The function is internally declared with global variables.
13: Static variables for functions with static declarations
14: Variable variable $ $a, $ ($a)
15: Predefined constants: __file__,true,false,null,
16: Predefined variables: $_server
17: Values are passed by reference.
18: function returns multiple values, with an array ...
19: If a function or operation must make a type, you must first determine the type, and then execute the code. The foreach function is slightly, what is judged by the Is_array ...

This article links http://www.cxybl.com/html/wlbc/Php/20130616/38660.html