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PHP Arrays Ex. #2: Simple Array Loop

For this exercise, you will use a list of ten of the largest cities in the world. (Please note, these are not the ten largest, just a selection of ten from the largest cities.) Create an array with the following values: Tokyo, Mexico City, New York City, Mumbai, Seoul, Shanghai, Lagos, Buenos Aires, Cairo, London.

Print these values to the browser separated by commas, using a loop to iterate over the array. Sort the array, then print the values to the browser in an unordered list, again using a loop.

Add the following cities to the array: Los Angeles, Calcutta, Osaka, Beijing. Sort the array again, and print it once more to the browser in an unordered list.

 

Here's the code:

  1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  2.      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  3.  
  4. <html xmlns="http://www.w3.org/1999/xhtml"  xml:lang="en" lang="en">
  5. <head>
  6. <meta http-equiv="content-type" content="text/html;charset=iso-8859-1" />
  7. <title>Simple Array Loop - Cities</title>
  8. </head>
  9.  
  10. <body>
  11. <h2>Large Cities<br /></h2>
  12.  
  13. <?php
  14. //Create array.
  15. $cities=array(
  16.   "Tokyo",
  17.   "Mexico City",
  18.   "New York City",
  19.   "Mumbai",
  20.   "Seoul",
  21.   "Shanghai",
  22.   "Lagos",
  23.   "Buenos Aires",
  24.   "Cairo",
  25.   "London" 
  26.   );
  27.  
  28. //Print values of array to browser, separated by commas. 
  29. foreach($cities as $c){
  30.   echo "$c, ";
  31. }
  32.  
  33. //Sort array.
  34. sort($cities);
  35.  
  36. //Print array as bulleted list.
  37. echo "\n<ul>\n" ;
  38. foreach($cities as $c){
  39.   echo "<li>$c</li>\n";
  40. }
  41. echo "</ul>" ;
  42.  
  43. //Add four cities to array.
  44. array_push($cities, "Los Angeles", "Calcutta", "Osaka", "Beijing") ;
  45.  
  46. //Sort again, and print bulleted list.
  47. sort($cities);
  48. echo "\n<ul>\n";
  49. foreach($cities as $c){
  50.   echo "<li>$c</li>\n";
  51. }
  52. echo "</ul>";
  53. ?>
  54.  
  55. </body>
  56. </html>

See the output of the script in a separate window here. You can also view the output's HTML source from the new window, if you need to check that.

To open a PHP code editor in a new tab, click here.

Comments

Submitted by anonymous on Tue, 07/26/2011 - 17:22.

Hello.

Whouldn't it have been better to sort using asort(), in order to preserve the key association?

Submitted by spfastjr on Sat, 11/04/2017 - 16:32.

The key association in this assignment really doesn't matter because it's not an associative array.

Submitted by steiner on Wed, 09/19/2012 - 07:18.

Hi, thanks for the great site!

I'd like to make some esthetics addition.
The comma in the end of the first array print makes it look untidy. Nevertheless, putting If Statement in the Foreach Loop to check for the end of array seems to be untidy as well. So I think it's bit better this way:

foreach ($cities as $c) {
$txt .= "$c, ";
}
unset($c);
$txt=rtrim($txt,", ");
echo "$txt.";

Don't know if it's the best solution, but still looks better.

Submitted by ericjric on Wed, 03/27/2013 - 01:22.

I don't think it looks too untidy. :P

  1. for ($i=0; $i<=9; $i++){
  2.     if ($i<9){echo $cities[$i].', ';}
  3.     else {echo $cities[$i];}
  4. }

Submitted by vinayak on Mon, 11/12/2012 - 02:35. 
  1. <?php
  2.  
  3. $cities = array('Tokyo', 'Mexico City', 'New York City', 'Mumbai', 'Seoul', 'Shanghai', 'Lagos', 'Buenos Aires', 'Cairo', 'London');
  4.  
  5. foreach ($cities as $key => $value) {
  6. 	//Determine the array size [alternative: count()]
  7. 	$last = sizeof($cities);	
  8. 	echo $value;
  9. 	//As first index key starts at 0, the last key is total size -1
  10. 	echo ($key == $last - 1) ? "." : ", ";
  11. }
  12.  
  13. echo "<br />";
  14.  
  15. sort($cities);
  16. echo "<ol>";
  17. foreach ($cities as $value) {
  18. 	echo "<li>$value</li>";
  19. }
  20. echo "</ol><br />";
  21.  
  22.  
  23. array_push($cities, 'Los Angeles', 'Calcutta', 'Osaka', 'Beijing');
  24. sort($cities);
  25. echo "<ul>";
  26. foreach ($cities as $value) {
  27. 	echo "<li>$value</li>";
  28. }
  29. echo "</ul><br />";
  30.  
  31. ?>

Submitted by boksa on Thu, 12/20/2012 - 11:54. 
  1. <html xmlns="<a href="http://www.w3.org/1999/xhtml"">http://www.w3.org/1999/xhtml"</a> xml:lang="en" lang="en">
  2.  
  3. 	<head>
  4. 		<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
  5. 		<title>Arrays Ex. #2</title>
  6. 	</head>
  7.  
  8. 	<body>
  9. 		<?php
  10. 		$cities = array("Tokyo", "Mexico City", "New York City", "Mumbai", "Seoul", "Shanghai", "Lagos", "Buenos Aires", "Cairo", "London");
  11. 		$countcities = count($cities);
  12. 		for($key = 0; $key < $countcities; $key++){
  13. 			echo " $cities[$key],";
  14. 		}
  15. 		echo "<br/>";
  16. 		sort($cities);
  17. 		?>
  18. 		<ul>
  19. 			<?php
  20. 			for($key = 0; $key < $countcities; $key++){
  21. 				echo "<li>$cities[$key]</li>";
  22. 			}
  23. 			?>
  24. 		</ul>
  25. 		<ul>
  26. 			<?php
  27. 			$cities1 = array("Los Angeles", "Calcutta", "Osaka", "Beijing");
  28. 			$cities2 = array_merge($cities, $cities1);
  29. 			sort($cities2);
  30. 			$countcities2 = count($cities2);
  31. 			for($key = 0; $key < $countcities2; $key++){
  32. 				echo "<li>$cities2[$key]</li>";
  33. 			}
  34. 			?>
  35. 		</ul>
  36. 	</body>
  37. </html>

Submitted by Md.Mir Masuk on Mon, 01/21/2013 - 03:32. 
  1. <?php
  2.  
  3. $cities=array("Tokyo", "Mexico City", "New York City", "Mumbai", 
  4.     "Seoul", "Shanghai", "Lagos", "Buenos Aires", "Cairo", "London");
  5.  
  6. asort($cities);
  7. foreach ($cities as $key => $value)
  8.     {
  9.  
  10.    echo  "<ul><li>$value,</li></ul>"; 
  11.  
  12.  
  13.  
  14. }
  15. echo"</br>";
  16.  
  17. array_push($cities, 'Los Angeles'," Calcutta", "Osaka", "Beijing");
  18. asort($cities);
  19.  
  20. foreach ($cities as $key => $value) {
  21.  
  22.     echo  "<ul><li>$value,</li></ul>"; 
  23.  
  24.  
  25.  
  26. }
  27. echo "<br />";
  28.  
  29.  
  30.  
  31.  
  32. ?>

Submitted by Joe Play on Thu, 09/26/2013 - 08:04.

tried to keep it as short as possible but that "period" really called for an extra line of code.

  1. <?php
  2. $city_names=array('Tokyo','Mexico City','New York City','Mumbai','Seoul','Shanghai','Lagos','Buenos Aires','Cairo','London');
  3. $strcount=count($city_names);
  4. foreach ($city_names AS $cn){
  5. 	echo "$cn";			
  6. 	if (($strcount-=1)==0) echo ".";
  7. 	else echo ", ";	
  8. 	}
  9. sort($city_names);
  10. foreach ($city_names AS $cn)
  11. 	echo "<li>$cn</li>";
  12.  
  13. echo"<br/>";
  14. array_push($city_names,'Los Angeles','Calcutta','Osaka','Beijing');
  15. sort($city_names);
  16. foreach ($city_names AS $cn)
  17. 	echo "<li>$cn</li>";
  18. ?>

Submitted by bl3k on Sat, 08/16/2014 - 10:17.

solve comma problem using ternary operator

  1. <?php
  2.  
  3. $largestCities = array(
  4. 	'Tokyo',
  5. 	'Mexico',
  6. 	'New York',
  7. 	'Mumbai',
  8. 	'Seoul',
  9. 	'Shanghai',
  10. 	'Lagos',
  11. 	'Buenos Aires',
  12. 	'Cairo',
  13. 	'London',
  14. );
  15.  
  16. // comma (,)
  17. for ($i=0; $i < count($largestCities); $i++) {	
  18. 	echo $largestCities[$i] . (($i < count($largestCities) - 1) ? ', ' : '');
  19. }
  20.  
  21. // sort array
  22. sort($largestCities);
  23.  
  24. echo '<br />';
  25. echo '<ul>';
  26.  
  27. for ($i=0; $i < count($largestCities); $i++) {	
  28. 	echo '<li>' . $largestCities[$i] . '</li>';
  29. }
  30.  
  31. echo '</ul>';
  32.  
  33. // add values to array
  34. array_push($largestCities, 'Los Angeles', 'Calcutta', 'Osaka', 'Beijing');
  35. sort($largestCities);
  36.  
  37. echo '<br />';
  38. echo '<ul>';
  39.  
  40. for ($i=0; $i < count($largestCities); $i++) {	
  41. 	echo '<li>' . $largestCities[$i] . '</li>';
  42. }
  43.  
  44. echo '</ul>';