Todays Outline Arrays Files Functions 1 Arrays <!DOCTYPE - - PDF document

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Todays Outline Arrays Files Functions 1 Arrays <!DOCTYPE - - PDF document

Feb 13, 2024 117 likes •231 views

IT360: Applied Database Systems PHP Arrays, Files, Functions Todays Outline Arrays Files Functions 1 Arrays <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"

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IT360: Applied Database Systems PHP Arrays, Files, Functions

Today’s Outline

  • Arrays
  • Files
  • Functions
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Arrays

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11//DTD/xhtml11.dtd"> <html xmlns = "http://www.w3.org/1999/xhtml"> <head><title>IT360 Arrays</title></head> <body> <?php require_once('array_functions.inc.php'); //create array $products = array('Tires','Oil'); $products[2] = 'Sparc Plugs'; //display array display_array('The content of $products array is:',$products); //create associative array $prices = array('Tires'=>100,'Oil'=>10); $prices['Spark Plugs'] = 4; //display associative array display_assoc_array('The content of $prices array is:', $prices); //sort array sort($products); display_array('The content of $products array in sorted order is:',$products); //make a copy of the array $prices2 = $prices; ksort($prices); display_assoc_array('The content of $prices array sorted by key is:', $prices); asort($prices2); display_assoc_array('The content of $prices array sorted by values is:', $prices2); ?> </body></html>

array_functions.inc.php

<?php function display_array($caption, $array){ echo "<h3> $caption </h3> <p>"; for($i=0; $i< count($array); $i++){ echo "Element $i is $array[$i] <br />"; } echo '</p>'; } function display_assoc_array($caption, $array){ echo "<h3> $caption </h3> <p>"; foreach($array as $key => $value){ echo "Current element is $key with value $value <br />"; } echo '</p>'; } ?>

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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