PHP：速记if - 结果未显示完整值

I dont understant why the second value in my button is not completely displayed

<p><input type ="button" id="comment" 
        value=<?php echo $comment_exist == null ? 'Save' : 'Cancel my comment'; ?>></p>

if condition is true, Save is displayed if not Cancel is displayed but not my comment.

Do you know why ? Thank you for your help

You'l need to quote your values. Either in single quote or double. And always have a practice of closing "self-closing" tags />

<p>
 <input type ="button" id="comment" 
    value="<?php echo $comment_exist == null ? 'Save' : 'Cancel my comment'; ?>" />
</p>

Try this (adding quotes)

<p><input type ="button" id="comment" 
        value="<?php echo $comment_exist == null ? 'Save' : 'Cancel my comment'; ?>"></p>

Try to quote this php code like this may be it will work

<p><input type ="button" id="comment" value="<?php echo $comment_exist == null ? 'Save' : 'Cancel my comment'; ?>"></p>