Combine multiple php bootstrap alert box into one - php

Question

i have a form which show error inside bootstrap alert, if username exist and if email exist. like in picture
now my question in how do i show alert in one single alert box
code
if (strlen($_POST['username']) < 3) {
$error[] = 'Username is too short.';
} else {
$stmt = $conn->prepare('Database query');
if (!empty($row['username'])) {
$error[] = 'Username provided is already in use.';
}
}
if (!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
$error[] = 'Please enter a valid email address';
} else {
$stmt = $conn->prepare('Database query');
if (!empty($row['email'])) {
$error[] = 'Email provided is already in use.';
}
}
/ alert box
if (isset($error)) {
foreach ($error as $errors) {
echo "<div class='alert alert-danger small text-center' role='alert'>" . $error . "</div>";
}
}
if (isset($_GET['action']) && $_GET['action'] == 'joined') {
echo "<div class='alert alert-success small text-center' role='alert'>Registration successful.<br> Please check your email to activate your account.</div>";
}
i tried adding $error[] .= but still din't work, any solution.
this is how i want my alert box to be

Answer 1

try this
<?php
if (strlen($_POST['username']) < 3) {
$error[] = 'Username is too short.';
} else {
$stmt = $conn->prepare('Database query');
if (!empty($row['username'])) {
$error[] = 'Username provided is already in use.';
}
}
if (!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
$error[] = 'Please enter a valid email address';
} else {
$stmt = $conn->prepare('Database query');
if (!empty($row['email'])) {
$error[] = 'Email provided is already in use.';
}
}
// alert box
if (isset($error)) {
$errorMsg = "<div class='alert alert-danger small text-center' role='alert'><ul>";
foreach ($error as $errors) {
$errorMsg .= '<li>' . $error . '</li>';
}
$errorMsg .= '</ul></div>';
echo $errorMsg;
}