To demonstrate some of the things you can do with arrays, I made an array of country codes and country names. I put it in a file by itself so I can use it in several other pages using include(). The array I'll use is $country_code and is located in country_codes.php. You can see the source code on country_codes_c.php. As you can see, it is an associative array of country names indexed by their country codes.
If you are adding members to an array and taking them away you can loose track of how many members are in the array. To find out how many there are you can use count(). After I made te array $country_code, I wondered how many countries were in it. Instead of counting them, I included the file with it in the top of this page:
<?
include("arrays/country_codes.php");
?>
Now that $country_code is on this page, I can use count() to tell me how many countries are in the list:
<?
$num = count($country_code);
echo "There are 0 countries in the array.";
?>
There are 0 countries in the array.
foreach() is a way to loop through an array executing a block of code for each member. The syntax is
<?
foreach ( $array as $index=>$member )
{
/* code block to be executed */
}
?>
$array is the array you are working on. $index and $member are temporary holders for the index/member pair foreach() is working with. The following code uses foreach() to output $country_code in this table:
<? include("country_codes.php"); ?>
<html>
<body>
<center>
<table border="5">
<tr>
<th>Code</th>
<th>Country</th>
</tr>
<?
foreach ( $country_code as $code=>$country )
{
echo "<tr>";
echo "<td align=\"center\">$code</td>";
echo "<td>$country</td>";
echo "</tr>";
}
?>
</table>
</center>
</body>
</html>
With PHP, you can sort an array several ways. For this example, I will use asort() to sort the members of $country_code. The example above outputted a table organized by the country code. If you wanted to organize it by country name instead, you could just switch $code and $country
<?
foreach ( $country_code as $code=>$country )
{
echo "<tr>";
echo "<td align="center">$country</td>";
echo "<td>$code</td>";
echo "</tr>";
}
?>
but in the resulting table, the country names would not be alphabetical. asort() will take a string and sort it alphabetical by member, keeping the original index. As in the example above, include the file with the array but before using foreach to output the table, use asort() to sort it.
<? include("country_codes.php"); ?>
<html>
<body>
<center>
<table border="5" cellpadding="5">
<tr>
<th>Country</th>
<th>Code</th>
</tr>
<?
asort($country_code);
foreach ( $country_code as $code=>$country )
{
echo "<tr>";
echo "<td>$country</td>";
echo "<td align=\"center\">$code</td>";
echo "</tr>";
}
?>
</table>
</center>
</body>
</html>
You can search through an array by its index to find a value associated with the index like a file cabinet. To search $country_code we first need a form:
<form>
<input cols="2" maxlength="2" type="text" name="in" value="" />
<input type="submit" />
<input type="text" name="country" value="" />
</form>
Put a block of PHP at the top of your page to grab any input from the form and assign it to a variable and include the array you want to search. Use an if statement to check if the variable is set.
<?
include("country_codes.php");
$in = $_REQUEST[in];
if ( isset() )
{
/* search block */
}
?>
The user may have entered the country in capital letters so the first thing to do is use strtolower() to change the input to lower case. Next, assign an error message to $country. If a match is found, the error message will be overwritten by the country name; if not, the error message is displayed
<?
$in = strtolower($in);
$country = "No match";
?>
And now, the search begins! Using foreach(), we enter the array $country_code and assign two variables to hold the index/value pairs as foreach() loops through $country_code. For the code block to be executed for each member, enter an if statement that tests if the input is the same as the index and if it is, assign that country name to $country.
<?
foreach ( $country_code as $key=>$val )
{
if ( $in == $key )
{ $country = $val; }
}
?>
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