title: How to define global constant char pointer in C and redefine poiting value throughout files
body: <p>i'm quite new in C, what i'm trying to do is define a pointer with a constant address, this is my attempt in testHeader.h:</p>
  
  <pre><code>char const *MY_VAR_P = (char * const)(0x4fffff);
  extern char MYVAR;
  </code></pre>
  
  <p>then in the global of test.c (but i got in mind to reuse the same pointer with same address in other .c files...):</p>
  
  <pre><code>#include "testHeader.h"
  
  char MYVAR = '0'; 
  *MY_VAR_P = MYVAR; 
  </code></pre>
  
  <p>and this is the error:</p>
  
  <pre><code>test.c:33: warning: type defaults to `int' in declaration of `MY_VAR_P'
  test.c:33: conflicting types for `MY_VAR_P'
  test.h:2: previous declaration of `MY_VAR_P'
  test.c:33: warning: initialization makes pointer from integer without a cast
  test.c:33: initializer element is not constant
  </code></pre>
  
  <p>I really don't understand...please someone can help me?</p>
  
  <p>thanks!</p>