const

What is the difference between char const * and char * const ?

According to the standard, const modifies the element directly to its left. The use of
 const  at the beginning of a declaration is just a convenient mental shortcut. So the following two statements are equivalent:

char const * pointerToConstantContent;
const char * pointerToConstantContent;

In order to ensure the pointer itself is not modifiable,  const  should be placed after the asterisk:

char * const constantPointerToMutableContent;

To protect both the pointer and the content to which it points, we should use two consts as below:

char const * const constantPointerToConstantContent;