PHP 5/MySQL Programming- P36 pdf
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$result = $distance[$cityA][$cityB];
print “<h3>The distance between $cityA and $cityB is $result miles.</h3>”;
?>
</body>
</html>
Building the Two-Dimensional Associative Array
The basic approach to building a two-dimensional array is the same whether it’s
a normal array or uses associative indexing. Essentially, you create each row as an
array and then build an array of the existing arrays. In the traditional array, the
indices were automatically created. The development of an associative array is a
little more complex, because you need to specify the key for each value. As an
example, look at the code used to generate the
$indy array:
$indy = array (
“Indianapolis” => 0,
“New York” => 648,
“Tokyo” => 6476,
“London” => 4000
);
Inside the array, I used city names as indices. The value for each index refers to
the distance from the current city (
Indianapolis) to the particular destination.
The distance from Indianapolis to Indianapolis is
0, and the distance from Indy
to New York is
648, and so on.
I created an associative array for each city and put those associative arrays
together in a kind of mega-associative array:
//set up master array
$distance = array (
“Indianapolis” => $indy,
“New York” => $ny,
“Tokyo” => $tokyo,
“London” => $london
);
This new array is also an associative array, but each of its indices refers to an array
of distances.
Getting Data from the
Two-Dimensional Associative Array
Once the two-dimensional array is constructed, it’s extremely easy to use. The
city names themselves are used as indices, so there’s no need for a separate array
to hold city names. The data can be output in two lines of code:
$result = $distance[$cityA][$cityB];
print “<h3>The distance between $cityA and $cityB is $result miles.</h3>”;
You can combine associative and normal arrays. It is possible to have a list of
associative arrays and put them together in a normal array, or vice versa. PHP’s
array-handling capabilities allow for a phenomenal level of control over your data
structures.
Manipulating String Values
The Word Search program featured at the beginning of this chapter uses arrays to
do some of its magic, but arrays alone are insufficient for handling the tasks
needed for this program. The
Word Search program takes advantage of a number
of special string manipulation functions to work extensively with text values.
PHP has a huge number of string functions that give you an incredible ability to
fold, spindle, and mutilate string values.
Demonstrating String Manipulation
with the Pig Latin Translator
As a context for describing string manipulation functions, consider the program
featured in Figures 5.10 and 5.11. This program allows the user to enter a phrase
into a text box and converts the phrase into a bogus form of Latin.
If you’re not familiar with pig Latin, it’s a silly kid’s game. Essentially, you take the
first letter of each word, move it to the end of the word, and add
ay.
If the word
begins with a vowel, simply end the word with
way.
The pigify program uses a number of string functions to manipulate the text:
<!doctype html public “-//W3C//DTD HTML 4.0 //EN”>
<html>
<head>
<title>Pig Latin Generator</title>
</head>
TRICK
TRICK
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<body>
<h1>Pig Latin Generator</h1>
<?
if ($inputString == NULL){
print <<<HERE
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FIGURE 5.10
The pigify
program lets the
user type some text
into a text area.
FIGURE 5.11
The program
translates immortal
prose into
incredible silliness.
<form>
<textarea name = “inputString”
rows = 20
cols = 40></textarea>
<input type = “submit”
value = “pigify”>
</form>
HERE;
} else {
//there is a value, so we’ll deal with it
//break phrase into array
$words = split(“ “, $inputString);
foreach ($words as $theWord){
$theWord = rtrim($theWord);
$firstLetter = substr($theWord, 0, 1);
$restOfWord = substr($theWord, 1, strlen($theWord));
//print “$firstLetter) $restOfWord <br> \n”;
if (strstr(“aeiouAEIOU”, $firstLetter)){
//it’s a vowel
$newWord = $theWord . “way”;
} else {
//it’s a consonant
$newWord = $restOfWord . $firstLetter . “ay”;
} // end if
$newPhrase = $newPhrase . $newWord . “ “;
} // end foreach
print $newPhrase;
} // end if
?>
</body>
</html>
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Building the Form
This program uses a PHP page to create an input form and to respond directly to
the input. It begins by looking for the existence of the
$inputString variable. This
variable does not exist the first time the user gets to the page. In this situation, the
program builds the appropriate HTML page and awaits user input. The program
runs again after the user hits the
submit button, but this time the $inputString
variable has a value. The rest of the program uses string manipulation functions to
create a pig Latin version of the input string.
Using the split() Function to
Break a String into an Array
One of the first tasks for pigify is to break the entire string that comes from the
user into individual words. PHP provides a couple of interesting functions for this
purpose. The
split() function takes a string and breaks it into an array based on
some sort of delimiter, or separator character. The
split() function takes two argu-
ments. The first argument is a delimiter and the second is a string to break up.
I want each word to be a different element in the array, so I use space (
“ “) as a
delimiter. The following line takes the
$inputString variable and breaks it into an
array called
$words. Each word is a new array element.
$words = split(“ “, $inputString);
Once the $word array is constructed, I stepped through it with a foreach loop. I
stored each word temporarily in
$theWord inside the array.
Trimming a String with rtrim()
Sometimes when you split a string into an array, each array element still has the
split character at the end. In the pig Latin game, there is a space at the end of
each word, which can cause some problems later. PHP provides a function called
rtrim() which automatically removes spaces, tabs, newlines, and other white-
space from the end of a string. I used the
rtrim() function to clean off any trail-
ing spaces from the
split() operation and returned the results to $theWord.
$theWord = rtrim($theWord);
In addition to rtrim(), PHP has ltrim(), which trims excess whitespace from
the beginning of a string and trim(), which cleans up both ends of a string. Also,
there’s a variation of the trim commands that allows you to specify exactly which
characters are removed.
TRICK
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