PHP Session Variable Array - php

Question

Hi I'm trying to understand session variables, in particular using them with arrays. In the example code below, the user enters a letter and I want to add that submission to a session variable so that the next time the user submits a letter I don't lose the previous entry.
So if the user enters 'e' the array displays 'e', and if the user then picks 's' then the array will now display 'e' and 's'. This is my first experiment with PHP and sessions are proving a little difficult to wrap my head around. Can anyone help me understand how to go about getting the result I want, or where I have gone wrong in the code below? Many thanks in advance.
<?php
session_start();
function example()
{
$_SESSION['lettersGuessed'] = array();
$userLetter = $_GET['input'];
array_push($_SESSION['lettersGuessed'],$userLetter);
print_r($_SESSION['lettersGuessed']);
}
if (strlen($_GET['input'])==1) {
if (ctype_lower($_GET['input']))
{
echo "The user-submitted letter is lowercase.<br>";
example();
}
else
{
echo "Invalid submission<br>";
}
}
?>
<form action="" method="get">
<input name="input" value="Enter a letter!" />
<input type="submit" value="Submit" />
</form>

Answer 1

try it out without array_push in a more simple way
There is a simple change in example function.
Following is complete code
<?php
session_start();
function example() {
$userLetter = $_GET['input'];
$_SESSION['lettersGuessed'][] = $userLetter;
print_r($_SESSION['lettersGuessed']);
}
if (strlen($_GET['input']) == 1) {
if (ctype_lower($_GET['input'])) {
echo "The user-submitted letter is lowercase.<br>";
example();
} else {
echo "Invalid submission<br>";
}
}
?>
<form action="" method="get">
<input name="input" value="Enter a letter!" />
<input type="submit" value="Submit" />
</form>
?>

Answer 2

The problem is that your line in the beginning of example() resets the session variable to a blank array every time the function is called.
Update your example() function as follows:
function example()
{
$_SESSION['lettersGuessed'][] = $_GET['input'];
print_r($_SESSION['lettersGuessed']);
}
Thankfully, PHP is loosely-typed, so you don't have to manually define lettersGuessed as an array. Simply using [] afterwards will cause it to be handled as an array, and then using the = assignment operator will push $_GET['input'] into it.