How to add GET and remove - php

Question

I have more GET variables. I want the variables to be added after clicking. And after clicking again I want them to be removed from GET. I am a beginner and I don't know how to do it.
<?php
$tab_array['name1']=1;
$tab_array['name2']=2;
$tab_array['name3']=3;
$tab_array['name4']=4;
$url=$_SERVER[QUERY_STRING];
if(!empty($url)){
$url="&".$url;
}
?>
<form action="" method="GET">
<?php
foreach($tab_array as $key => $val){
?>
<?php echo $key;?>
<?php
}
?>
</form>
Someone will help?
Sorry for my bad English...

Answer 1

Code
<?php
$tab_array['name1']=1;
$tab_array['name2']=2;
$tab_array['name3']=3;
$tab_array['name4']=4;
$url='?'; // this will call the current url
// $_GET is the array your submitted data will be strored in - initially empty []
?>
<form method='GET'><!-- you actually don't need a form, since only input, textarea, etc get submitted -->
<?php
// save current state, so you can modify it for every possible click
$current_get = $_GET;
foreach($tab_array as $key => $value) {
$new_get = $current_get;
// check if the current key is already in your set ($new_get)
if (array_key_exists($key, $new_get)) { // it is, so remove
unset($new_get[$key]);
} else { // it is not, so add
$new_get[$key] = $value;
}
// build your query_string (from $new_get array)
$query_string = http_build_query($new_get);
// you can use variables in string when its encapsulated in double quotes: "text $var"
echo "<a href='$url$query_string'>$key</a>";
// more readable:
// echo "<a href='{$url}{$query_string}'>{$key}</a>";
// not need but looks better :P
echo '<br />' . PHP_EOL;
}
?>
</form>
A little more
there is a shortcut for <php echo $var ?> which is just <?= $var ?>
Links
array_key_exists
unset
http_build_query