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PHP Arrays Ex. #5: Associative Array

Ex6

In this PHP exercise, you will again use the list of cities in Arrays Exercise #2. Here's the list, this time including countries as well as cities:

Tokyo, Japan; Mexico City, Mexico; New York City, USA; Mumbai, India; Seoul, Korea; Shanghai, China; Lagos, Nigeria; Buenos Aires, Argentina; Cairo, Egypt; London, England.

This time, create an associative array, using the countries as keys, the cities as values. Create a form for the user, with the instructions Please choose a city:

Follow this request with a select field for the 10 cities, with the options created by looping through the array. When the user clicks the submit button, return the statement $city is in $country., where $city is the value chosen by the user, and $country is its key.

Comments

Really like your website.

Permalink Submitted by MISTEROUIJA on Mon, 03/11/2013 - 09:57.

I Really like your website. It's nice to have exercises to do to test what you've learnt.

Here is my solution.


<h2>Associative Array</h2>
<?php

//create associative array
$cities = array(
	'Japan'=>'Tokyo',
	'Mexico'=>'Mexico City',
	'USA'=>'New York City', 
	'India'=>'Mumbai',
	'Korea'=>'Seoul',
	'China'=>'Shanghai',
	'Nigeria'=>'Lagos', 
	'Argentina'=>'Buenos Aires', 
	'Egypt'=>'Cairo', 
	'England'=>'London' 
	);
	if(!isset($_POST['submit'])){	
?>

<form method="post" action="arraystwo.php">
	<p>
	Please choose a city:
	<select name="city" size="1" >
		<?php
		//loop through array to create options
		foreach($cities as $x){
		echo "$x";
		}
		?>
	</select>
	</p>
	<p><input type="submit" name="submit" value="Send" /></p>
</form>
<?php
}
else{
//Get user selection
$city = $_POST['city'];
//Flip array so the keys become the value
$country = array_flip($cities);

echo "<p>$city is in $country[$city]</p>";

}
?>

I really like your solution

Permalink Submitted by Bladeoz on Mon, 08/05/2013 - 01:22.

I was stuck with attempting to pull out the key from the array. I tried several different functions to no avail, but your idea of flipping the array is brilliant.

Thank you a million!

(FYI: I attempted to create a function that could be reused to display the form, and ask users to type in the city name to get the Country they required, just for fun). Not sure I should post consider it's off on a tangent.

array_search not returning any data

Permalink Submitted by vanquish12 on Fri, 07/12/2013 - 04:03.

I can only get array_search to return the key when I put in the literal text of the value field, e.g. London. It will not work if I substitute the $_POST variable, or the variable that I assign to the $_Post variable. My code is below, if you can help! Thank you.

```
 <?php
```
```
 
```
```
$places = array(
```
```
	"Japan" => "Tokyo",
```
```
    "Mexico" => "Mexico City",
```
```
    "USA" => "New York City",
```
```
    "India" => "Mumbai",
```
```
    "Korea" => "Seoul",
```
```
    "China" => "Shanghai",
```
```
    "Nigeria" => "Lagos",
```
```
    "Argentina" => "Buenos Aires",
```
```
    "Egypt" => "Cairo",
```
```
    "UK" => "London");
```
```
 
```
```
 
```
```
?>
```
```
 
```
```
Please pick a city:
```
```
<form action="" method="post">
```
```
	<select name="city">
```
```
<?php
```
```
	foreach ($places as $key => $value) {
```

?>	<option value=" <?php echo $value ; ?>"><?php echo $value;

```
}?>
```
```
	</select>
```
```
	<input type="submit">
```
```
</form>
```
```
 
```
```
 
```
```
<?php
```
```
 
```
```
if(isset($_POST['city'])) {
```
```
 
```
```
		$ciudad = $_POST['city'];
```

		$country = array_search($_POST['city'], $places);

		echo "You have chosen" . $_POST['city'] . ", which is in" . $country;

```
 
```
```
 
```
```
 
```
```
 
```
```
 
```
```
} else {
```
```
	echo "no";
```
```
}
```

multiple selection capable

Permalink Submitted by Joe Play on Sat, 09/28/2013 - 06:35.

Here is my take for this exercise. You can select multiple entries, and all corresponding results will be displayed. It is short and simple.

```
<html>
```

<head><title>Select Field Exercise - Joe Play</title></head>

```
<body>
```
```
	<?php		
```

		$places=array('Japan'=>'Tokyo','Mexico'=>'Mexico City','USA'=>'New York City','India'=>'Mumbai',

		'South Korea'=>'Seoul','China'=>'Shanghai','Nigeria'=>'Lagos','Argentina'=>'Buenos Aires',

		'Egypt'=>'Cairo','England'=>'London');

```
 
```

		if (!empty($_POST["selectedPlace"])) {

			foreach($_POST["selectedPlace"] as $selectedCity){

				foreach($places as $country => $city)

					if($city==$selectedCity) echo"$city is in $country.<br/>";

```
			}
```
```
		}		
```

		echo"<br/>Please choose a city: <br/>(Press and hold CTRL key for multiple selection)<br/>";

```
		echo"<form action='' method='post'>";
```

			echo"<select name='selectedPlace[]' multiple='yes' size='".count($places)."'>";

				foreach($places as $country => $city){

					echo"<option value=\"$city\">$city</option>";

```
				}
```
```
			echo"</select>";
```

			echo"<br/><input type='submit' value='Check it!' />";

```
		echo "</form>";
```
```
	?>							
```
```
</body>
```
```
</html>
```

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