title: Error of wrong char, even when the char is correct
body: <p>I have an assignment on matrix operations and I cannot figure out what is wrong in my code, that makes my program say that char is wrong, even though it is correct. Could you please help me?
  Thank You.</p>
  <pre><code>if(scanf(&quot; %c&quot;, &amp;symbol) == 1)              //input symbol with error handling
      {
          if (symbol != '*' || symbol != '+' || symbol != '-')
          {
              printf(&quot;[%c]\n&quot;, symbol);
              fprintf(stderr, &quot;Error: Chybny vstup [Symbol]!\n&quot;);
              return 100;
          }
      }  
  </code></pre>
  <p><a href="https://i.stack.imgur.com/RiebL.png" rel="nofollow noreferrer">enter image description here</a></p>