PHP Notes - Java programmers understand PHP programs

I think PHP is a loosely typed language, so variables do not have specific type keywords when they are declared. uniformly start with

$ + variable name

1,

must be letters or _

starting with

can only contain alphanumeric characters and underscores

Right size Write-sensitive 5. Variables can be declared anywhere in the

PHP script. 6.  Referenced Scripts used by

/ - Scope

                                                          local(local)

b) Overall)

c)                                                                                                                                                                     Variables declared outside functions have global functions Domain, which can only be accessed outside the function. Variables declared inside a function have

local scope and can only be accessed within the function. function internal call

globalVariables need to be declared internally with the global keyword; ②

$GLOBAL[index] All global variables are stored in , which can be obtained through super global variables $GLOBAL[index]. 7.  $GLOBAL[index]This array can be accessed within the function and can be used to directly update global variables.

8.                                                                                                                                                                                                             to be deleted after the function completes execution. If you do not need to delete it, you need to use static9. $,

in script Its value cannot be changed in . By define("name of constant","value of constant

","Whether the constant name is case-sensitive Sensitive ”);true( same case )insensitive, falsesensitive. To define constants in a class, use the const keyword. 　　 A constant that changes depending on where it is used becomes a magic constant. Le 1) __file__ current folder 2) __Line__ Current number 3) __function__ The current function name 4) __Class__ The current class name ) __Method__ Print: echo can output more than one string. print

can only output a string and always returns

1

. 11. String lengthstrlen();Retrieve the specified characters or text within the string

strpos(); String concatenation uses ".","

." must be followed by spaces. 12. Super global variable:

a) $ globals

All variables in the global scope. b)                                                                  Information about headers, paths, and script locations. c)                                                                                                         

HTMLData submitted by form. d)                                                                                        Widely used to collect submissionsmethod=”post” HTML

The form data after the form is also commonly used to pass variables. e)                                                     For collecting submissionsHTMLform (method=” The form data after get”) can also collect the data sent in the URL.

f)                                                      Upload files from client computer to remote server. g)                                                                        Get the server-side environment parameters. Le (variables_order = epgcs) $_Cookie

to retrieve Cookie The value of . i)                                                                           Used to store information about a user session, or to change the settings of a user session.

13. include/require statement will get all the text that exists in the specified file / Code/

tag, and copied to the file using the include/require statement. a)                                                                  , when an error occurs, a fatal error will be generated and the script will stop. When an error occurs, only a warning will be generated. Continue execution.

c)                                                                                     Contain the same page only once. 14. Array processing:

$Array name[' Key name'] to initialize the array; you can also create an array through the

Array() function. count()Returns the length of the array. Array traversal: foreach loop, use count() to get the length of the array and then use for;list()

;each() returns key-value pairs.

while(list($key,$value)=each($array)){ } foreach( $array as $key => $value){

}

15.

PHP中Class objects are declared with the

class keyword. Class attributes also have scopes. If you do not specify a scope, you can use

var

to modify it. The difference between member methods and functions is that you can Modify with keywords. Constructor__contract,

Destructor__destruct16. "::" ​​​​ scope operator, which can call constants, variables and methods in a class without instantiation; " 

Array member access symbol; "->" Object member access symbol ;

"=&"                                                                                                  “=

”    Assignment. 17.

$Variable name = new Class name ([parameters

]);                                                                                                                                             

$Variable name->Member attribute = value ;                                                         Assign a value to the attribute; $

Variable name->Member attribute;                                                                                          Get attribute value;$Variable name->

Member method;                                                                                                                  How to use; 18. mysql: General useconn.php

Encapsulate, then use require

3)                                                                                                                                                                                                                                                                                                              

5) Returnsql Statement result set; 6)                                                                                                                                                                          

7)    echo "

Field name: ".$v['title'];

                                                      }9)                                                                                                                                                              10)

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