PHP Learning Note One

PHP/*three ways to annotate 2014/7/24 ctrl+j copy the current line*/   #  //  Echo"Hello World";//output A string  Echo"<br/>";//2. Define variables to start with $$a= 890;//defines a variable $ A, where the data type is determined by the context of the runtime//php is case-sensitive$b;//so the system doesn't allocate space for $b .Var_dump($b);//Output <null>Echo $a;Echo"<br/>";Var_dump($a);//variable information can be displayed  Echo"<br/>";$a= 1.1;//the value below will overwrite the previous value.$a= "Hello World";//It covers not only the value but also the type.Var_dump($a); Echo"<br/>"; /*Shaping in PHP can start with decimal, octal 0, Hex 0X*/$a 1= 0123;//octalEcho' a1= '.$a 1;//. Concatenation of the represented stringEcho"<br/>";/*PHP does not support unsigned integers, that is, the integers in PHP are signed (binary)*/EchoPhp_int_size//can display the local machine, an integer expressed in several bytesEchoPhp_int_max//can display the maximum shape value//negative and positive number as large, if more than the shaping range will be automatically converted to other types of values?>

PHP Learning Note One