title: Implicit declaration of function is invalid in C99
body: <p>I am new to C language and I am having a problem that I  really don't understand. I am trying to get an array from another function but when I try to extract the information, it gives me the following warning: </p>
  
  <blockquote>
    <p>Implicit declaration of function 'getk_vector_calculation' is invalid in C99
    Array initializer must be an initializer list or string literal</p>
  </blockquote>
  
  <p>Here is the code:</p>
  
  <pre><code>int k_vector_calculation(int krec[3])
  
  {
      ...
  
      krec [0] = l*u[0]+m*v[0]+o*[0] ;
  
      krec [1] = l*u[1]+m*v[1]+o*[1] ;
  
      krec [2] = l*u[2]+m*v[2]+o*[2] ;
  
      return k_vector_calculation( &amp;krec[3] ) 
  
  }
  
  int main ()
  
  {
  
      char krec[3] = getk_vector_calculation(&amp;krec[3]); 
  
      ...
  
  }
  </code></pre>