Question

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Why does C have a distinction between -> and . ?

What is the real reason for a programmer to have to differentiate between . and -> when accessing a member of an object?

void foo( Point &p ) {
    p.x ;
    p->y; // syntax error
} 

void foo( Point *p ) {
    p.x ; // syntax error
    p->y;
} 

I mean, one way or another, they both refer to an object, p.

• Why do I have to bother checking every time what p is ? Can’t the compiler understand ?

• Why haven’t they allowed it to accept . syntax for both? That would be fine for stack objects too.

And if it is due to C-tradition,

• Why don’t they allow both . and -> accessors?

For more than 15 years, I have always humbly considered the compiler errors as being my fault !

Answer 1

Because p->d actually means (*p).d. It does a dereference and then a member access. References behave like objects thus they don’t need dereferencing (they are also a C++ feature, while pointer are inherited from C); it has been kept that way for backwards compatibility.

C++ is full of inconsistencies like this, but there’s usually no better choice to add new features and keep old code working. Rewriting the old code is not an option.