Use of variables in php learning_PHP tutorial-PHP Tutorial-php.cn

Use of variables in php learning_PHP tutorial

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Release： 2016-07-21 15:29:03

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//Quote
$one="test"; 
two=&$one;//Equivalent to passing an address, two variables point to one address

//Dynamic variable
$one="######"; 
$ two="one"; 
$three="two"; 

echo $three."
";//Output "two" 
echo $$three."< br>";//Output "one" 
echo $$$three."
";//Output "######" 

//There are 8 in php Type
//4 types of scalars: int integer 
// bool boolean 
// float, double, real 
// string 
//2 types of composite types: array 
/ / object 
//2 special types: resource type resource 
// empty type null 


//declaration of integer
$int=10; //declaration of decimal
$int=045;//Octal declaration
$int=0xff;//Hexadecimal declaration
$float=3.14E+5;//Scientific notation
$float=3.14E -5; 

//All cases are false
$bool=false; 
$bool=0; 
$bool=0.000; 
$bool=null; 
$bool=""; 
$bool=" "; 
$bool="0"; 
$bool=array(); 

//String declaration
//1. Both single quotes and double quotes can declare strings
//2. There is no length limit for the declared strings
//3. In double-quoted strings, variables can be parsed directly , and you can use escape characters directly (you can escape the single quote itself, or you can escape the escape character "") 
//4. In a single-quoted string, variables cannot be parsed directly, nor can Use escape characters 
//5. Double quotes can no longer be used within double quotes, and single quotes can no longer be used within single quotes 
//6. It is best to use single quotes, 
$str=' aaaaa'; 
$str="aaaa"; 
//Delimiter declares a string, a large number of strings 
//test is a custom string, there cannot be any characters after it, and there are no spaces. No
//It must also end with the custom string test, and there cannot be any characters before the end
$str=<<this write content... 
test; 
?> 