Ternary operator and other operators
There are also some special operators and symbols, let us explain. We may need to use later. Linear motor selection
| symbol | Explanation |
|---|---|
| ? $ X really snippet: false code segment | Determine whether the case is true or false true: false cases;? |
| `` (Backtick) | Backticks interposition of substituting commands, execute system commands, functions equivalent to shell_exec |
| @ | Single-line error suppression, this line is wrong not to let it show out, inefficient use is not recommended |
| => | Array subscript accessors |
| -> | Object Access Fu |
| instanceof | Determine if an object from a class, if the return is true, and false if not |
Ternary operator, if ... else equivalent structures. However, the ternary operator wording more concise, the following syntax:
? $ X really snippet (can only write a code): pseudo-code segment (can only write a code);
code show as below:
<?php $x = true; $x ? $y = 5 : $y = 6; //输出5 echo $y; ?>
Backticks even more special, we often need to display the IP address, we can not display windows of the IP address in PHP inside it? With anti-quotation marks, we can execute commands (though some virtual servers are prohibited execute these commands script):
<?php echo '<pre>'; echo `ipconfig`; echo '</pre>'; ?>
You execute the code above to see the effect, it is not displayed and a bunch of IP addresses and IP related parameters of your machine?
@ Symbol refers to a single line to suppress errors in subsequent chapters we will explain to. To understand the level here.
<? PHP // adfsafasdfasfasdfdsadf.txt open a file that does not exist, you will find that running about the error. @ @ Again in front of a symbol plus see the effect of $ FP = the fopen ( 'adfsafasdfasfasdfdsadf.txt', 'R & lt'); // @ $ FP = the fopen ( 'adfsafasdfasfasdfdsadf.txt', 'R & lt'); ?>
Array subscript operator access, will also have a chapter to explain, here to learn what you can:
<? PHP $ = Data Array ( 'siNA' => 'Sina', 'sohu' => 'Sohu'); ?>
Object Access Fu -> instanceof and understand all levels, and they will have a special section to explain:
? <PHP
// instantiate an object
$ obj = new new StdClass ();
// a determination is made an object instance of a class, is performed if it is true
IF (the instanceof the stdClass $ obj) {
echo 'true';
the else {}
echo 'false';
}
// append to the object obj property is a member of the username
$ obj -> username = 'PHP Chinese network';
echo $ obj -> username;
>?
All the above example, in addition to the ternary operator, @, Backspace. Other levels are learning to understand, explain at a later time. You know this symbol can be.