title: error: invalid operands to binary expression
body: <p>I have a struct which I initialized = NULL here:</p>
  
  <pre><code>void inicializa(tabelaHash **tabela, int tamanhoTabela) {
      int i;
      for(i = 0; i &lt; tamanhoTabela; i++) {
          inicializaArvore(&amp;tabela[i]);
      }
  </code></pre>
  
  <p>My problem is that, when I test if it worked, with "if(tabela[i] == NULL) ..." on a function as the one I mentioned or any other that needs a "**tabela", it works just fine, but, when I do it on my main, it gets me this error:</p>
  
  <pre><code>main.c:129:16: error: invalid operands to binary expression ('tabelaHash'
    (aka 'struct sbb') and 'void *')
              if(tabela[k] == NULL)
                 ~~~~~~~~~ ^  ~~~~
  </code></pre>
  
  <p>the line that gets this error is just:</p>
  
  <pre><code>    for (k = 0; k &lt; tamanhoTabela; k++) {
      129-&gt;if(tabela[k] == NULL)
          printf("funcionou");
  }
  </code></pre>
  
  <p>tabela is a hash table of binary trees, tabelaHash is a struct sbb (sbb is a kind of binary tree defined as follows: </p>
  
  <pre><code>struct sbb {
  tipoItem reg; //that is the information it holds
  struct sbb *esq; // left pointer
  struct sbb *dir; // right pointer
  int esquipo; // if it is a vertical or horizontal pointer to the left
  int dirtipo; // if it is a vertical or horizontal pointer to the right
  </code></pre>
  
  <p>};</p>
  
  <p>I want to have a pointer that points to the root of each tree on the "tabela[i]", so I malloc'ed as follows:</p>
  
  <pre><code>tabelaHash *tabela;
  tabela = malloc(tamanhoTabela * sizeof(tabelaHash*));
  </code></pre>
  
  <p>How do I test if tabela[i] is still NULL on my main?</p>
  
  <p>edit: I don't know if that is of any help, but I have just realized that I can only use the "if(tabela[i] == NULL)" on a function if the function calls for a "tabelaHash **". If I call for a "tabelaHash *", than it gets me the same error.</p>