title: declaring a struct in .h file and implementing in .c file
body: <p>this is my .h file:   </p>
  
  <pre><code>struct _MyString;  
  typedef struct _MyString MyString;
  </code></pre>
  
  <p>i would like to declare its members in the .c file.</p>
  
  <p>i tried:  </p>
  
  <pre><code>typedef struct MyString{
      char * _str;// pointer to the matrix
      unsigned long _strLength;
      }MyString;
  </code></pre>
  
  <p>but it doesn't work.
  how do i declare the struct's memebers in the .c file?</p>
  
  <p>thank you</p>