PHP: Difference between revisions

Latest revision as of 18:43, 28 April 2017

Manual

http://www.php.net/manual/en/

Example

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
   "http://www.w3.org/TR/2000/REC-xhtml1-20000126/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
   <meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
   <title>Blank PHP Script</title>
</head>
<body>
<?php
echo "<h1>Here is a heading</h1>";
?>
</body>
</html>

Comments

# single line
// single line
/* multiple
   line */

Constants

define("PI", 3.14159); print PI;   # outputs 3.14159

Scalar Variables

# four scalar types: boolean, integer, float, string
$value = "Here is some text.";
$message = "Memory: {$memory}MB";  # curly braces separate variable from context

Conditional Expressions

# 0, "0", null, and unset are false, otherwise true
# conditional expressions evaluate the same way as Java
# === and !== test for equivalence of both value and type
("10 feet" == 10) but ("10 feet" !== 10)

Flow Control

if ($var > 5)
    print "Variable greater than 5";
elseif ($var < 0)
    print "Variable is negative.";
else {
    print "Variable is positive and less than or equal to 5";
    print "Here is some more text";
}
# switch, while, do while, and for loops are identical to Java
# use of break and continue is same as in Java

Type Casting

(bool), (int), (float), (string) to cast type
# gettype( ), print_r( ), and var_dump( ) give type information

Functions

function bold($string) {
    print "<b>" . $string . "</b>";
}
# static variable
function count( ) {
    static $count = 0;
    return $count++;
}
# pass by reference
function doublevalue(&$var) {
    $var = $var * 2;
}
# default parameter value
function heading($text, $headingLevel = 2){
    ...
}

Functions in include files

Here is functions.inc

function bold($string) {
    print "<b>" . $string . "</b>";
}

Here is how to use it:

include("functions.inc");   # warn if not found
require("functions.inc");   # error if not found

String Manipulation

$var = $var . " string";                   # concatenation (like Perl)
$length = strlen($my_string);              # string length
$words = explode(" ", "Now is the time");  # tokenize on space character
$array_string = implode(", ", $array);     # comma-separated values
printf("Result: %.2f\n", $pi);             # print formated to output buffer
$output = sprintf("Result: %.2f\n", $pi);  # return formatted string
print str_pad("PHP", 6);                   # prints "PHP   "
print strtolower("PHP and MySQL");         # php and mysql
print strtoupper("PHP and MySQL");         # PHP AND MYSQL
print ucfirst("now is the time");          # Now is the time
print ucwords("now is the time");          # Now Is The Time
print trim(" Tiger Land \n");              # "Tiger Land"
print ltrim(" Tiger Land \n");             # "Tiger Land \n"
print rtrim(" Tiger Land \n");             # " Tiger Land"
# string comparison
print strcmp("aardvark", "zebra");         # -1
print strcmp("zebra", "aardvark");         #  1
print strcmp("mouse", "mouse");            #  0
print strcmp("mouse", "Mouse");            #  1
print strncmp("aardvark", "aardwolf", 4);  #  0
print strncmp("aardvark", "aardwolf", 5);  # -1
print strcasecmp("mouse", "Mouse");        #  0
# substrings
print substr("abcdefgh", 2);               # "cdefgh"
print substr("abcdefgh", 2, 3);            # "cde"
print substr('abcdef', -1, 1);             # "f"
print substr("abcdefgh", -5, -2);          # "def"
print strpos("abcdefgh", "de");            # 3
print str_replace("teh", "the", "In teh beginning...");

Arrays

# array length
print count($array);
# keys are integers by default
$numbers = array(5, 4, 3, 2, 1);
print $numbers[2];       # prints 3
$words = array("Web", "Database", "Applications");
print $words[0];         # prints "Web"
$shopping = array( );    # create empty array
$shopping[] = "Milk";    # add elements to the end of the array
$shopping[] = "Coffee";
$shopping[] = "Sugar";
print "The first item in my list is {$shopping[0]}";  # use {} inside quotes
# strings can be used as keys, like a Perl hash
$array = array("first"=>1, "second"=>2, "third"=>3);
print $array["second"];  # prints "2"
# removing an element from an array with unset doesn't reassign keys
unset($words[1]);        # $words[2] is still "Applications"
unset($words);           # destroys entire array
# the values of an array can be arrays or objects, too
$planets = array(
    "Mercury"=> array("dist"=>0.39, "dia"=>0.38),
    "Venus"  => array("dist"=>0.72, "dia"=>0.95),
    "Earth"  => array("dist"=>1.0,  "dia"=>1.0,
                      "moons"=>array("Moon")),
    "Mars"   => array("dist"=>0.39, "dia"=>0.53,
                      "moons"=>array("Phobos", "Deimos"))
    );
print $planets["Earth"]["moons"][0];  # prints "Moon"
print "The {$planets2["Earth"]["moons"][0]} is a balloon";  # still need {}
# iterate over an array's values
foreach ($array as $value){
    # do something with $value
}
# iterate over an arrays key/value pairs
foreach ($array as $key => $value){
    # do something with key, value
}

Array Functions

# array size
print "array size: " . count($array); # prints number of elements
# value frequency
$pets = array("Beth"=>"Dog", "Arabella"=>"Rabbit", "Meg"=>"Cat", "Neda"=>"Cat");
$petFrequency = array_count_values($pets);
print_r($petFrequency);  # Array ( [Dog] => 1 [Rabbit] => 1 [Cat] => 2 )
# create an array with all the same values
$unity = array_fill(1, 10, "one");
# create an array with incremented values
$letters = range("A", "F");
# min, max values
$min = min($numbers); $max = max($numbers);
# true if haystack contains needle
if (in_array($needle, $haystack)) print "found it";
# find the key for a given value
$key = array_search($value, $array);  # return false if not found
# WARNING: the first element of an integer-key array will return 0.
# Distinguish this from boolean false using the === operator

# true if key exists
if (array_key_exists($key, $array)) print "found it";
# get a list of keys for an array
$keys = array_keys($array);
# get a list of values for an array
$values = array_values($array);
# strip out non-unique values from an array
$unique_values = array_unique($array);
# concatenate two arrays
$big_array = array_merge($array1, $array2);
# reverse the order of an array
$reversed = array_reverse($array);
# sort/reverse-sort the elements of an array (does not return a copy)
sort($array); rsort($array);
# sort/reverse-sort an associative array on values
asort($array); arsort($array);
# sort/reverse-sort an associative array on keys
ksort($array); krsort($array);
# sort with a user-defined comparison function
function length_compare($a, $b){
    if (strlen($a) < strlen($b)) return -1;
    if (strlen($a) > strlen($b)) return 1;
    return 0;
}
usort($array, "length_compare");  # sort by values, assign new indices
uasort($array, "length_compare"); # sort by values, keep old keys
uksort($array, "length_compare"); # sort by keys, keep old values

Regular Expressions

$found = ereg('\.com', "www.ora.com");      # true
$found = ereg("[ABC][123]", "A1 Quality");  # true
$found = ereg("[^0-9a-zA-Z]", "123abc");    # false
# eregi is same as ereg but case insensitive
$valid_email = eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email);    
# Perl-based regular expression matching
$found = preg_match('\.com', "www.ora.com");  # true

Dates and Times

print time( );                           # 1064699133 (seconds since 1/1/1970)
$aDate = mktime(8, 15, 0, 6, 23, 1972);  # 8:15am on 6/23/1972 (local time)
$var = strtotime("25 December 2002");
$var = strtotime("14/5/1955");
$var = strtotime("Fri, 7 Sep 2001 10:28:07 -1000");
print strtotime("+1 day");               # tomorrow
print strtotime("-2 weeks");             # two weeks ago
print strtotime("+2 hours 2 seconds");   # in two hours and two seconds
print date('d/m/Y', $date);              # "24/08/1974"
print date('m/d/y', $var);               # "08/24/74"
$valid = checkdate(1, 1, 1066);          # true
$valid = checkdate(1, 1, 2929);          # true
$valid = checkdate(13, 1, 1996);         # false
$valid = checkdate(4, 31, 2001);         # false
$valid = checkdate(2, 29, 1996);         # true
$valid = checkdate(2, 29, 2001);         # false

Math

Just as in perl or java.

File I/O

$filename = "/home/paul/test.txt";      # unix
$filename = "c:\\paul\\test\\test.txt"; # windows
# dump a file to the screen
if (!@readfile($filename)) {   # '@' supresses error output to screen
    print "Could not open $filename.\n";
}
# read file to a string, complete with newline characters
$filestring = file_get_contents($filename);
if ($filestring) {
    print $filestring;
} else {
    print "Could not open $filename.\n";
}
# read file into an array
$filearray = file($filename);
if ($filearray) {
    while (list($var, $val) = each($filearray)) {
        ++$var;
        $val = trim($val);
        print "Line $var: $val<br />";
    }
} else {
    print "Could not open $filename.\n";
}
# write a string to a file (PHP < 5)
function file_write_string($file, $string){
    $fh = fopen($file, "wb");
    $string .= "\n";
    fwrite($fh, $string);
    fclose($fh);
}
# append a string to a file (PHP < 5)
function file_append_string($file, $string){
    $fh = fopen($file, "ab");
    $string .= "\n";
    fwrite($fh, $string);
    fclose($fh);
}
# write an array/string to a file (PHP >= 5)
$numbytes = file_put_contents($filename, $mydata);  # mydata is string or array
print "$numbytes bytes written\n";
# append to a file (PHP >= 5)
$numbytes = file_put_contents($filename, $mydata, FILE_APPEND);
# rename/move a file
$filename2 = $filename . '.old';
$result = rename($filename, $filename2);
# copy a file
$filename2 = $filename . '.old';
$result = copy($filename, $filename2);
# delete a file
$result = unlink($filename);
# check for existence
$result = file_exists($filename);
# filename deconstruction
$fileinfo = pathinfo($filename);  # array contains dirname, basename, extension

Form Processing

Example form:

<form action="process.php" method="post">
<select name="item">
<option>Paint</option>
<option>Brushes</option>
<option>Erasers</option>
</select>
Quantity: <input name="quantity" type="text" />
<input type="submit" />
</form>

process.php:

$quantity = $_POST['quantity'];
$item = $_POST['item'];
echo "You ordered ". $quantity . " " . $item . ".<br />";

Sending Email

$status = mail('barney@somehost.com', 'About your message', $message);

Redirect

<?php
header( 'Location: http://www.yoursite.com/new_page.html' ) ;
?>

Debugging

# to write the error stream to the web page, edit php.ini to include this:
display_errors = On
# WARNING: this should be Off in a production site

# to see server settings:
print phpinfo();

print_r($variable);   # shows keys and values
var_dump($variable);  # shows keys, values, and types

@@ Line 132: / Line 132: @@
 print strpos("abcdefgh", "de");            # 3
 print str_replace("teh", "the", "In teh beginning...");
-<source>
+</source>
 == Arrays ==

PHP: Difference between revisions

Latest revision as of 18:43, 28 April 2017

Contents

Manual

Example

Comments

Constants

Scalar Variables

Conditional Expressions

Flow Control

Type Casting

Functions

Functions in include files

String Manipulation

Arrays

Array Functions

Regular Expressions

Dates and Times

Math

File I/O

Form Processing

Sending Email

Redirect

Debugging

Navigation menu

PHP: Difference between revisions

Latest revision as of 18:43, 28 April 2017

Manual

Example

Comments

Constants

Scalar Variables

Conditional Expressions

Flow Control

Type Casting

Functions

Functions in include files

String Manipulation

Arrays

Array Functions

Regular Expressions

Dates and Times

Math

File I/O

Form Processing

Sending Email

Redirect

Debugging

Navigation menu

Search