Why can't variable names start with numbers?

c++ variables programming-languages language-design variable-names
Jeremiah picture Jeremiah · Dec 4, 2008 · Viewed 96k times · Source

I was working with a new C++ developer a while back when he asked the question: "Why can't variable names start with numbers?"

I couldn't come up with an answer except that some numbers can have text in them (123456L, 123456U) and that wouldn't be possible if the compilers were thinking everything with some amount of alpha characters was a variable name.

Was that the right answer? Are there any more reasons?

string 2BeOrNot2Be = "that is the question"; // Why won't this compile?

Answer

Pyrolistical picture Pyrolistical · Dec 4, 2008

Well think about this:

int 2d = 42;
double a = 2d;

What is a? 2.0? or 42?

Hint, if you don't get it, d after a number means the number before it is a double literal

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