title: FILE, fopen etc... error. file is NULL
body: <p>I am trying to read a file which is located at the same source as my .c code. I tried this little sketch and same problem. What could be wrong?
  File's extension and name are just the same.</p>
  
  <pre><code>#include &lt;stdlib.h&gt;
  #include &lt;stdio.h&gt;
  
  int main (){
      char caracter;
      FILE *ARCHIVO;
      ARCHIVO=fopen("prueba.txt", "r");
      if (ARCHIVO==NULL){
          printf("Error·");
      }else{
          while (feof(ARCHIVO)==0){
              caracter=fgetc(ARCHIVO);
              printf("%c", caracter);
          }
      }
      fclose(ARCHIVO);
      return 0;
  }
  </code></pre>
  
  <p>I will be very thankful if someone could help me. 
  Regards.</p>