C++ style: Stroustrup' s placement of pointer asterisks
C++ emphasis heavily on types and when it comes to pointers declaration, to avoid any sort of confusion, Bjarne suggested -
Stick to one pointer per declaration.
From Bjarne Stroustrup's C++ Style and Technique FAQ [emphasis added]:
int* p;right or is
Both are "right" in the sense that both are valid C and C++ and both have exactly the same meaning. As far as the language definitions and the compilers are concerned we could just as well say
int * p;
The choice between
int *p;is not about right and wrong, but about style and emphasis. C emphasized expressions; declarations were often considered little more than a necessary evil. C++, on the other hand, has a heavy emphasis on types.
typical C programmerwrites
int *p;and explains it
*p is what is the intemphasizing syntax, and may point to the C (and C++) declaration grammar to argue for the correctness of the style. Indeed, the
*binds to the name
pin the grammar.
typical C++ programmerwrites
int* p;and explains it
p is a pointer to an intemphasizing type. Indeed the type of
int*. I clearly prefer that emphasis and see it as important for using the more advanced parts of C++ well.
The critical confusion comes (only) when people try to declare several pointers with a single declaration:
int* p, p1; // probable error: p1 is not an int*
*closer to the name does not make this kind of error significantly less likely.
int *p, p1; // probable error?
Declaring one name per declaration minimizes the problem - in particular when we initialize the variables. People are far less likely to write:
int* p = &i;
int p1 = p; // error: int initialized by int*
And if they do, the compiler will complain.
Whenever something can be done in two ways, someone will be confused. Whenever something is a matter of taste, discussions can drag on forever. Stick to one pointer per declaration and always initialize variables and the source of confusion disappears.
See The Design and Evolution of C++ for a longer discussion of the C declaration syntax.
I cannot speak for Bjarne, but tying the asterisk (and ampersand in case of reference) to the type makes sense because being a pointer is semantically part of the type of the variable. The name of the variable is
p and its type is
int*. The name is not
*p and the type is not
It is nearly always possible to avoid multiple variable declarations in a single declaration, so that is not an issue.
In my opinion, this approach is clearer, especially in case of return types:
T* function(Args...); T *function(Args...);