Question

Why was C++ designed such that the correct way to declare two int *s on the same line is

int *x, *y;

not

int* x,y;

I know some people think you should avoid either form and declare every variable on its own line, but I’m interested in why this language decision was made.

Answer 1

To keep compatibility with C code, because that’s how C works.

Bjarne makes a good point in his style and technique faq:

The choice between int* p; and 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.

A typical C programmer writes int *p; and explains it *p is what is the int emphasizing 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 p in the grammar.

A typical C++ programmer writes int* p; and explains it p is a pointer to an int emphasizing type. Indeed the type of p is int*. I clearly prefer that emphasis and see it as important for using the more advanced parts of C++ well.

So, the motivation for this working as this in C++ is how it works in C.

The motivation it works like that in C is that, as stated above, C emphasizes expressions rather than types.