PHP5.4 syntax, constants, variables, data types

1. Basic grammar and writing format of php5.4

Opening of the short label mode:

; Short_open_tag

The delimiter for the PHP statement;

<?php$php=true;if ($php) {echo "It is true";//Semicolon description}//curly brace End;?>

Use the format of the function:

1. Return value function name ()

2. Return value function name (parameter, parameter ...) ）

3, Function name (parameter, parameter:, return variable)

4. Return value function name (...) ) The calling character

2. Variable and variable data type of php5.4

The variable starts with $, can only be a letter or an underscore, consisting of letters, numbers, underscores, numbers cannot begin

<?php$title= "php100.com",//true$title123= "php100.com";//true$123tiele= "php100";//error$_title= "php100.com" ;//true[email protected] #title = "php100";//error$url= "php100";//trueecho $url;//Output @urlunset ($url);//delete variable Urlecho $ Url No data output?>

Scheme for variable naming:

1. Direct connection between $titlekeyword words

2, $title _keyword words directly with _ link

3, $titleKeyword the first letter of the word capital

Data type:

1. String single quotation mark (simple quotation mark) or double quotation mark (functional quotation mark)

2, Plastic integer-2147 4836 48 to +2147 4836 47 (32-bit)

3, float type float or double 1.8E+308

4 Boolean Boolean True or False

5. Arrays Array

6. Object

7. Resource type resource system data resources

3. System constants and custom constants for php5.4

Start with a letter or an underscore, divided into system constants and custom constants

System constants:

__file__ PHP program file name and path

__line__ Functions of PHP programs

Name of the __class__ class

Custom constants:

BOOL Define ("name", "value")

<?phpdefine ("Color", "red"), Echo COLOR. " <br> ";? >

Practice part:

Can be mixed with HTML code

Last line can not write semicolon

<?php$abc= "php100.com"; Echo $abc;? >

Variable Value re-assignment

<?php$abc= "php100.com"; $abc = "www.php100.com"; Echo $abc;? >

Variable variable

<?php$a= "B"; $ $a = "123"; echo $b;? >

The output of the string

<?php echo ' 00000000000 ';? >

Escaped single quotation mark

<?php echo ' 0000\ ' 0000000\\ ';? >

Output I Hava

<?php$a=50;echo "I Hava $a";? >

Output I Hava $a

<?php$a=50;echo ' I hava $a ';? >

int -

<?php$a=50;var_dump ($a);? >

string ' # ' (length=2)

"<?php$a="; var_dump ($a);? >

float 3.14

<?php$a=3.14;var_dump ($a);? >

Boolean true

<?php$a=true;var_dump ($a);? >

Boolean false

<?php$a=false;var_dump ($a);? >

Array (size=4) 0 = int 2 1 = int 3 2 = int 4 3 = int 5

<?php$a=array (2,3,4,5); Var_dump ($a);? >

string ' 123ABC ' (length=6)

<?php$a= "123ABC"; var_dump ($a);? >

int 123

<?php$a= "abc123"; $b = (int) $a; var_dump ($b); >

int 0

<?php$a= "abc123"; $b = (int) $a; var_dump ($b); >

Boolean true

<?php$a=1; $b = (bool) $a; Var_dump ($b);? >

Boolean false

<?php$a=0; $b = (bool) $a; Var_dump ($b);? >

Boolean false

<?php$a= ""; $b = (bool) $a; Var_dump ($b); >

Boolean true

<?php$a= "ASDFGHR"; $b = (bool) $a; Var_dump ($b); >

System variables

9
C:\wamp\www\a_com\test.php

<?phpecho __line__. " <br> "; Echo __file__;? >

System Customization

123

<?phpdefine ("NA", "123"), Echo NA; >

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