How is "L" macro(?) defined?

Question

static TCHAR szWindowClass[] = L"foo";

L is "glued" to the string "foo". How come? A function or a macro as I am used to is something like L("foo");

Can anyone explain me how come L be glued to the string?

Answer 1

L is not a macro, it's just the standard prefix for wide (wchar_t, "Unicode") string literals; the concept is similar to the L suffix for long int literals, f suffix for float literals and so on¹.

By the way, if you are using TCHARs you shouldn't be using L directly; instead, you should use the _T() or TEXT() macro, that adds L at the beginning of the literal if the application is compiled "for Unicode" (i.e. TCHAR is defined as WCHAR), or adds nothing if the compilation target is "ANSI" (TCHAR defined as CHAR).

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1. Although in my opinion this is confusing - why suffixes for arithmetic types and a prefix for wide string literals?

Answer 2

It's not a macro, it's a token that the compiler recognizes as a prefix that has some special meaning.

The same happens with e.g. l as a suffix that produces long literals, as in long x = 42l;.