multiple select in 2 dimensional array in php - php

Question

In PHP, I am having 2 array
$ex1 = array(a,b,c,d,e,f,g,h);
$ex2 = array(c,e,f);
Here how can I integrate this with multiple select option in PHP page
Here ex1 is the multiple select array like
<select multiple name=slt[]>
</select>
And ex2 values are the chosen listing options

Answer 1

Something like:
<?php
$ex1 = array('a','b','c','d','e','f','g','h');
$ex2 = array('c','e','f');
echo "<select multiple name=slt[]>";
foreach($ex1 as $val){
//in_array() checks if value from 1st array ($val) is present
//anywhere in the second array ($ex2)
//if yes, that option will be selected. I'm using ternary operator
//here instead of if statement
$selected = (in_array($val,$ex2))?' selected':'';
echo "<option value='".$val."'$selected>".$val."</option>";
}
echo "</select>";
?>
PHP Demo
Output Fiddle

Answer 2

I'm not sure about what you want to do, but here's an idea :
$ex1 = array("a","b","c","d","e","f","g","h");
echo "<select multiple>";
foreach( $ex1 as $value ){
echo "<option value='$value'>$value</option>";
}
echo "</select>";

Answer 3

Try running it:
<?php
$ex1 = array('a','b','c','d','e','f','g','h');
$ex2 = array('c','e','f');
?>
<select multiple name=slt[]>
<?php
foreach ($ex1 as $option) {
$active = false;
foreach($ex2 as $selected){
if($option == $selected){
$active = true;
}
}
?>
<option value="<?php echo $option; ?>" <?php if($active===true) echo "selected"; ?>><?php echo $option; ?></option>
<?php
}
?>
</select>