title: Please Help me about "strcmp"
body: <p>I have slice of C code and I want to ask when I input some string for example "up". 
  Jump to the code looks like : <code>(strcmp(pdirection,"up")==0)</code><br>
  So, what does it mean, I don't understand especially <code>==0</code></p>
  
  <p>the slice of code is at call by reference position.</p>