What does it mean when var_dump reports the wrong string length?

I'm trying to figure out why a variable isn't triggering a conditional that it should. var_dump reports somethi开发者_StackOverflow中文版ng like this:

string(20) "0"

Why is it reporting a length of 20 when the length is clearly 1?

It might be rendering html. i.e. var_dump('<p class="abc">0</p>') would output string(20) "0" to the naked eye