Three points of code analysis that cannot be ignored in PHP development

Recently I have discovered that many PHP programmers, especially those who have not studied for a long time, do not know the essence of PHP. PerlHow did you become famous in the business world back then? Its powerful regular expressions. And what about PHP? It is a language developed under Unix. Of course, it inherits many features of Perl and has the advantages of C. Fast, concise, and clear, especially C programmers, PHP is a favorite. Here, I want to write an article on PHP's variables, arrayapplication skills and PHP's regular expressions and PHP's template applications.
1. Application skills of variables and arrays(1) Arrayfunction
that is rarely used by many people. foreach, list, each. Just give a few examples and you should be able to figure it out. Example:

$data = array('a' => 'data1', 'b' => 'data2', 'c' => 'data3'); 
while(list($subscript, $value) = each($data)) 
{ 
echo "$subscript => $value :: "; 
echo "$subscript => $valuen
"; 
} 
reset($data); 
foreach($data as $subscript => $value) 
{ 
echo "$subscript => $value :: "; 
echo "$subscript => $valuen
"; 
}

(2) Variables of functions, variables of variables, "pointers" of variables: See the following example:

//变量的变量 
$var = "this is a var"; 
$varname = "var"; 
echo $$varname; 
//函数的变量 
function fun1($str) { 
echo $str; 
} 
$funname = "fun1"; 
$funname("This is a function !"); 
?>

"Pointers" of variables. This pointer is enclosed in double quotes, indicating that it is not a real pointer. Take a look at the following example:

function($a) { 
$a ++; 
} 
$c = 0; 
function($c); 
echo $c; //$c仍为0 
function(&$a) { 
$a ++; 
} 
$c = 0; 
echo $c; //$c为1 
?>

is called a "pointer" because it has the same function as the pointer in

C language

. But this is not a real pointer, it can only be understood in this way.
2. Regular expressions Regular expressions are a very big topic, and Perl's regular expressions are well-known for their power. PHP is not weak either. It inherits Perl's regular expression rules and has its own set of rules. Here we only talk about PHP's own regular expressions. Regular expressions are the most basic elements. Simply put, it is a set of rules used to determine whether
other
elements comply with its own rules, or whether they have the same characteristic description. The starting symbol of the regular expression: ^, the ending symbol $, the two symbols are the matching elements. For example, if you want to check whether a phone number is for Beijing, the regular expression would be "^010$". As long as the first three digits of the area code are 010, it is Beijing's number, and the following phone numbers are not needed. Then, use the regular expression matching function ereg to judge, for example:

$pattern = "^010$"; 
$phone = "01080718828"; 
if(ereg($pattern, $phone)) 
echo "打往北京的号"; 
else 
echo "不是打往北京的号"; 
?>

This is the regular expression. Phone numbers in Beijing are all 8 digits, so I need to know if the number is correct? What if he pressed the 9-digit number? If judged right or wrong? This requires the use of the

character cluster

of the regular expression. Then the regular expression in the above example should be written like this: ^010[0-9]{8}$, and it can be judged at the same time whether the number conforms to the rules. Regular expressions have many applications. For example, the so-called VBB code analysis in LBB and VBB forums when posting is all done using regular expressions.
3. Template If you know the function of regular expressions, you can know the template. What is a template? Give me an example? Generally, when a background program is used to write a web page, the program code is inserted into the web page. Such as PHP. This is a mix of HTML and PHP. The advantage of this is that the reading speed is fast, but the disadvantage is that if everyone works together to build the website, non-programmers will not change the website. The use of templates can achieve the most rational division of labor. The artist only writes the page, the program only writes the background, and then puts it all together. The excellent
Jsp
provides the function of self-defining tags and completes the template function well. And how does mainstream PHP do it? This is done using regular expressions. You can download a PHPLIB from the Internet. There is a source code file of template.inc in the PHP directory, which is a class that uses PHP to implement template application.

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