C++ beginner question: dereference vs multiply [duplicate]

Question

Just getting into C++. I'm getting constantly thrown off track when I see the symbol for multiply (*) being used to denote the dereferencing of a variable

for example: unsigned char * pixels = vidgrabber.getPixels();

Does this throw other people off? What's the tip for getting my head around this?

Thank you.

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p.s. I have another reasonably simple question, that didn't get answered :( here: beginner question: add/subtract to value rather than just be that value pretty please! and thanks for your time!

Answer 1

C, and by inheritance C++, are swamped with operators and are inherently context-sensitive. You will have to get used to it:

If * appears before the name of a variable that is being declared (or defined), it's a type modifier and makes that variable a pointer.
If it is a unary prefix operator for a variable that is part of an expression, it's dereferencing (or whatever it's been overloaded to).
If it is a binary infix operator for two variables that are part of an expression, it's multiplication (or whatever it's been overloaded to).

(From this you can see that the * in your unsigned char * pixel isn't a dereferencing unary prefix, but a type modifier.)

Note that & pretty much resembles *, only it's meaning is different: it makes a variable a reference, is the address-of operator, or the binary AND.

Answer 2

One recommendation when writing your own code is to "cuddle" the * when using as a pointer/deref:

unsigned char *pixels = ...

if (*pixels == ...)

and to space the * when using as a multiply:

int y = x * 7;

There are other clues you can use (such as the fact that pointer deref is a unary operator while multiple is a binary operator).