PHP

Appeared in:
1995
Influenced by:
Influenced:
Paradigm:
Typing discipline:
File extensions:
.php, .phtml .php3 .php4 .php5 .phps
Versions and implementations (Collapse all | Expand all):
Programming language

PHP, or PHP: Hypertext Preprocessor (PHP originally stood for “personal home page”), is a widely used, general-purpose scripting language that was originally designed for web development, to produce dynamic web pages.

It can be embedded into HTML and generally runs on a web server, which needs to be configured to process PHP code and create web page content from it.

PHP has evolved to include a command line interface capability and can also be used in standalone graphical applications.

Elements of syntax:

Inline comments # and //
Non-nestable comments /* */
Variable identifier regexp [a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*
Variable declaration with assignment $variable = value
Grouping expressions ( ... )
Block { ... }
Comparison < > <= >=
Function definition function f(a, b, ...) { ... }
Function call f(a, b, ...)
Function call with no parameters f()
Sequence ;
If - then if (condition) trueBlock
If - then - else if (condition) trueBlock else falseBlock
Loop forever while (true) loopBody
While condition do while (condition) loopBody
Do until condition do loopBody while (!condition)
For each value in a numeric range, 1 increment for ($i = first; $i <= last ; $i++) loopBody
For each value in a numeric range, 1 decrement for ($i = last; $i >= first; $i--) loopBody

Links:

Examples:

Factorial:

Example for versions PHP 5.2.4, PHP 5.3.2

This example uses recursive factorial definition. 

<?php
function factorial($n)
{
    if ($n == 0) {
        return 1;
    }
        
    return $n * factorial($n - 1);
}

for ($n = 0; $n <= 16; $n++) {
    echo $n . "! = " . factorial($n) . "\n";
}
?>

Hello, World!:

Example for versions PHP 5.2.4, PHP 5.3.2 
<?php
echo "Hello, World!\n";
?>

Fibonacci numbers:

Example for versions PHP 5.2.4, PHP 5.3.2

This example uses recursive definition of Fibonacci numbers. 

<?php
function fibonacci($n)
{
    if ($n < 3) {
        return 1; 
    }
    
    return fibonacci($n-1) + fibonacci($n-2);    
}

for ($n = 1; $n <= 16; $n++) {
    echo fibonacci($n) . ", ";
}
echo "...\n";
?>

Quadratic equation:

Example for versions PHP 5.3.2 
<?php

echo "A = ";
$A = (float) fgets(STDIN);
if ($A == 0) {
  die("Not a quadratic equation\n");
}

echo "B = ";
$B = (float) fgets(STDIN);
echo "C = ";
$C = (float) fgets(STDIN);

$D = $B * $B - 4 * $A * $C;

if ($D == 0) {
  echo "x = ", -$B / 2.0 / $A, "\n";
  die();
}
if ($D > 0) {
  echo "x1 = ", (-$B + sqrt($D)) / 2.0 / $A, "\n";
  echo "x2 = ", (-$B - sqrt($D)) / 2.0 / $A, "\n";
} else {
  echo "x1 = (", -$B / 2.0 / $A, ", ", sqrt(-$D) / 2.0 / $A, ")\n";
  echo "x2 = (", -$B / 2.0 / $A, ", ", -sqrt(-$D) / 2.0 / $A, ")\n";
}

?>

CamelCase:

Example for versions PHP 5.3.2

This example uses string functions and regular expressions. Function ucwords converts first letter of each word to uppercase. 

<?
$text = fgets(STDIN);
$text = str_replace(' ', '', ucwords(preg_replace('/[^a-z]/', ' ', strtolower($text))));
echo $text;
?>