title: Why a pointer + 1 add 4 actually
body: <pre><code>#include&lt;stdio.h&gt;
  int main(void){
    int *ptr,a,b;
    a = ptr;
    b = ptr + 1;
    printf("the vale of a,b is %x and %x respectively",a,b);
  
    int c,d;
    c = 0xff;
    d = c + 1;
    printf("the value of c d are %x and %x respectively",c,d);
    return 0;
  }
  </code></pre>
  
  <p>the out put value is</p>
  
  <pre><code>the vale of a,b is 57550c90 and 57550c94 respectively
  the value of c d are ff and 100 respectively%  
  </code></pre>
  
  <p>it turns out the ptr + 1 actually, why it behave this way?</p>