Php Basics-constant-variable-related basic functions-PHP Tutorial

Php Basics-constant-basic functions related to variables. Php Basics-constant-variable-related basic function annotation statement line # single line * multi-line comment *** document comment ** constant-defined custom Constant name case-sensitive system php Basics -constant-basic functions related to variables
Comment statement


// Single row


# Single row


/*
Multi-line comment
*/


/**
* Document comment
*
*/


Constant definition


Custom constant name case sensitive
The magic constant of the system is case insensitive _ DIR _ dir __




Variable definition
Variable names are case sensitive
The variable name must start with the $ symbol and comply with the naming rules of the variable name.






$ I;
Var_dump ($ I );


$ I = 'OK ';
Var_dump ($ I );




$ I = "Hello ";
Var_dump ($ I );




$ I = 20;
Var_dump ($ I );




USD I = 20.5;
Var_dump ($ I );


// The variable type is similar to the javascript variable type and is a variant type.
$ I = true;
Var_dump ($ I );






The function name and class name are case-insensitive.






Basic php functions


Phpinfo ();
Var_dump ($ I );
Echo gettype ($ I );
Define ('age', 200 );
Defined ('age ');


Realpath ()
Dirname ();

Comment statement // Single line # single line/* multi-line comment * // *** document comment **/constant definition custom Constant name case sensitive system...