PHP within an Echo PHP - php

Question

I have the following code, but the echo $jsonData[$i] line gives an error. I know you are not supposed to execute PHP within PHP. What is the correct way to accomplish this?
<?php
if( !is_user_logged_in() ){
echo 'Im online. Login to Chat';
} else {
echo '<input type=\"submit\" onclick=\"javascript:jqcc.cometchat.chatWith(' <?php echo $jsonData[$i]; ?> ');\" value=\"Chat Now\" class=\"success button small\"
\" >';
}
?>

Answer 1

You use the concatenation operator . instead of echo when you're already within the scope of a string:
echo '<input type="submit" onclick="javascript:jqcc.cometchat.chatWith(' . $jsonData[$i] . ');" value="Chat Now" class="success button small">';
Also, you don't need the backslashes unless you're using the same quotes to start and end the string. In your case you open/close with single quotes, so double quotes don't need to be escaped.

Answer 2

Once you're in PHP mode (i.e. reach the opening <?php tag), everything is read as code until you exit PHP mode (i.e. reach the closing ?> tag). So there's no need to reopen those tags when they've already been open. See the basic syntax section of the manual for more details about this.
One of PHP's best features is that it allows you to embed code in HTML, rather than having to embed HTML in code. It's actually much easier to read your code when you write it like this, for example...
<input type="submit" onclick="javascript:jqcc.cometchat.chatWith(<?= $jsonData[$i]; ?>);" value="Chat Now" class="success button small">
Notice we only use PHP to print the value of $jsonData[$i] where it's needed and everything else is just plain/text or HTML that gets printed.
Also, note I'm using the short-hand form of <?php echo which is just <?=.
To expand on this a little, one of the reasons this idea of embeding code in HTML is so useful, is that it allows you to easily and transparently separate code from data.
<?php
$loggedIn = is_user_logged_in();
if ($loggedIn) {
?>
<input type="submit" onclick="javascript:jqcc.cometchat.chatWith(<?= $jsonData[$i]; ?>);" value="Chat Now" class="success button small">
<?php
} else {
?>
<h1>ohnoes, you're not logged in :(</h1>
<?php
}