Todays Outline Arrays Files Functions 1 Arrays <?php - - PDF document

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IT360: Applied Database Systems PHP Arrays, Files, Functions

Today’s Outline

• Arrays
• Files
• Functions

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Arrays

<?php require_once('page.inc.php'); require_once('arrayFunctions.inc.php'); //create the page $myPage = new Page('Array examples'); //set the content $myPage->content = '<p>Working with Arrays</p>'; //create an array $array = array('thing1', 'thing2'); $array[2] = 'thing3'; $myPage->content .= '<p>'.displayArray($array) . '</p>'; //create associative array $prices = array('Tires' => 100, 'Oil' => 10); $prices[‘Spark plugs'] = 200; $myPage->content .= '<p>The values in $prices array are <br />’ . displayAssociativeArray($prices) . '</p>'; sort($array); //sort array $myPage->content .= '<p> Sorted array '.displayArray($array) . '</p>'; ksort($prices); //sort associative array by key $myPage->content .= '<p>The values in $prices array sorted by key are <br />' . displayAssociativeArray($prices) . '</p>'; asort($prices); //sort associative array by value $myPage->content .= '<p>The values in $prices array sorted by value are <br />' . displayAssociativeArray($prices) . '</p>'; //display page $myPage->display(); ?>

array_functions.inc.php

<?php //return a string to display an array function displayArray($array){ $result = ‘<p>'; for($i = 0; $i < count($array); $i++){ $result .= "Element at index $i is $array[$i] <br />"; } $result .= ‘</p>'; return $result; } //return a string to display an associative array function displayAssociativeArray($array){ $result = ‘<p>'; foreach($array as $key => $value){ $result .= "Element with key $key has value $value <br />"; } $result .= ‘</p>'; return $result; } ?>

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Class Exercise

• Create an array containing the following values:

(1900, 2000, 2004, 2005 ).

• Use the array in a “foreach” loop to test if the

value is a leap year.

• If it is a leap year print “XXXX is a leap year”
• Else print “XXXX is not a leap year”
• A year is a leap year if it is divisible by 4. If the

year is also divisible by 100 then it is NOT a leap year unless it is also divisible by 400. Thus, 1900 is not a leap year (divisible by 100 but not 400) while 2000 is a leap year (divisible by 400).

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Outline

• Arrays
• More About Files
• More About Functions

fopen() modes

r Read only. Starts at beginning of file r+ Read/Write. Starts at beginning of file w Write only. Opens and clears contents of file; or creates new file if it doesn't exist w+ Read/Write. Opens and clears contents of file; or creates new file if it doesn't exist a Write only. Opens and writes to end of file or creates new file if it doesn't exist a+ Read/Write. Preserves file content by writing to end of file x Write only. Creates new file. Returns FALSE and error if file already exists x+ Read/Write. Creates new file. Returns FALSE and error if file already exists

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More Files: Read Line from File

• string = fgets(filePointer, [maxLength])
• string = fgetss(filePointer, [maxLength]

[, allowableTags])

• array = fgetcsv(filePointer, [maxLength] [,

string delimiter])

Read Whole File

• int readfile(fileName)
• int fpassthru(filePointer)
• array file(fileName)
• string file_get_contents(fileName)

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Other Reads

• char fgetc(filePointer)
• string fread(filePointer, nbBytes)

Useful File Functions

• bool file_exists(fileName)
• int filesize(fileName)
• bool unlink(fileName)

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File Locking

function save_to_file($text, $fileName = "myFile.txt"){ $fp = @fopen($fileName, 'a'); if (!$fp){ echo "<p>ERROR: Could not open file $fileName. </p>"; return FALSE; } else{ flock($fp, LOCK_EX); fwrite($fp, $text); flock($fp, LOCK_UN); fclose($fp); return TRUE; } }

Class Exercise

• Create PHP script to:
• Open/create a file, without overwriting it
• Write the numbers 1 to 20 to file, separated

by space

• Close the file

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Outline

• Arrays
• More About Files
• More About Functions

Function Parameters

<?php function start_table($border, $cellspacing=2, $cellpadding=2){ echo “<table border = $border cellspacing = $cellspacing cellpadding = $cellpadding>”; } ?>

• start_table(2,3,4)
• start_table(1)
• start_table(2,3)

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Variables Scope

• Variables used in functions are visible from first

use line to end of function – local variables

• Variables used outside functions are visible from

first use line to end of file, but not inside functions – global variables

• Superglobal variables ($_POST, $_SERVER,

…) are visible everywhere

• Keyword global makes local variables global –

not recommended

Variables Scope Example

<?php function fn(){ $x = 'content'; } fn(); echo 'Value of $x is '. $x; ?>

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Variables Scope Example 2

<?php $x = 'content 1 <br/>'; echo 'Content of $x after initialization is '. $x . '<br />'; function fn(){ echo 'Content of $x at start of function is '. $x. '<br />'; $x = 'content 2 <br/>'; echo 'Content of $x at end of function is '. $x. '<br />'; } fn(); echo 'Value of $x after calling fn() is '. $x. ‘<br />'; ?>

Summary

• Arrays
• Numerically indexed
• Associative
• Sort
• Files
• Functions to work with files
• File locking
• Functions
• Optional parameters
• Variable scope