PHP警告：除零错误（temp tpl）

I am getting the following error:

Warning: Division by zero in /home/vaibongd/public_html/temporary/%%B0^B0F^B0FD4939%%right2.tpl.php on line 19

Line 19 is the first line in the code. I looked at some of the related questions and all my quote marks seem to be in the right place.

<?php if ($this->_tpl_vars['page'] == "" / vai / ""): ?>
            <div class="custom-block-content">
                <ul class="new_cungloai">
                    <?php unset($this->_sections['f']);

What am I doing wrong?

your if condition will not work, because / vai / is not escaped.
Try this:

if ($this->_tpl_vars['page'] == '" / vai / "'):

or if you just want / vai / use this:

if ($this->_tpl_vars['page'] == ' / vai / '):

if ($this->_tpl_vars['page'] == "\" / vai / \""): // Just add slashes to ignore the quotes conflict