Examples of the essence and techniques in PHP language_PHP tutorial

Many PHP programmers, especially those who have not studied for a long time, do not know the essence of PHP. How did Perl become famous in the business world? Its powerful regular expressions. 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 for C programmers, PHP is their favorite. I just love "PHP" deeply (I have forgotten my girlfriend). Here, I want to write about PHP variables and array application skills, PHP regular expressions, and PHP template applications. I will write about the complete combination of PHP and COM, and PHP and XML when I have time in the future.

1. Application skills of variables and arrays

(1) Array functions that are 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) Function variables, variables of variables, and "pointers" of variables:

//Variables of variables
$var = "this is a var";
$varname = "var";
echo $$varname;
//Variables of functions
function fun1($str) {
echo $str;
}
$funname = "fun1";
$funname("This is a function !");
?>

The "pointer" to the variable. 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 still is 0
function(&$a) {
$a ++;
}
$c = 0;
echo $c; //$c is 1
?> ;

The reason why it is called a "pointer" is 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 expression

Regular expressions are a very big topic, and Perl’s regular expressions are famous 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 conform to its own rules, or whether they have the same characteristic description.

The starting symbol of the regular expression: ^ and the ending symbol $. The elements between these two symbols are matched. For example, if you want to check whether a phone number is for Beijing, the regular expression would be "^010$". 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 "Call to Beijing";
else
echo "This is not a number bound for Beijing";
?>

This is a regular expression. Phone numbers in Beijing are all 8 digits, so I want to know if the number is correct? What if he pressed the 9-digit number? If it is correct or incorrect? This requires the use of regular expression character clusters. 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 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, 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.

With templates, you 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. Excellent Jsp provides the function of custom tags and completes the template function well. How does mainstream PHP do it? It uses regular expressions to do it. 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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