"Define" Macro Concatenation and _TEXT

Question

is there any way of concatenation #define macros in c++ (ms compiler)?

I have existing code like this:

#define LOG_FILENAME _TEXT("VendorBlaBlaDriver.log")
#define REGISTRY_FILENAME _TEXT("VendorBlaBlaDriver")
#define VENDOR_NAME _TEXT("VendorBlaBla")

I wanna do the following:

#define NAME_PART1 "VenorBlaBla"
#define NAME_PART2 "Driver"

#define LOG_FILENAME _TEXT(NAME_PART1 NAME_PART2 ".log")
#define REGISTRY_FILENAME _TEXT(NAME_PART1 NAME_PART2)
#define VENDOR_NAME _TEXT(NAME_PART1)

But compiler gives me an error:

error C2308: concatenating mismatched strings

Is there any way of doing this right? The thing is that's a component and I want to specify -D option to compiler later. I don't want to store NAME_PART1 and NAME_PART2 in source code.

possible duplicate of [C preprocessor and concatenation](http://stackoverflow.com/questions/1489932/c-preprocessor-and-concatenation) — Ólafur Waage, Jun 03 '11 at 09:49
You can simply type #define LOG_FILENAME NAME_PART1 NAME_PART2 ".log" or am I missing something? — 0xbadf00d, Jun 03 '11 at 09:56
Hint: If you follow the advice and use `_TEXT` multiple times, you can use the short `_T` macro, that expands to the same. — Xeo, Jun 03 '11 at 10:01

score 3 · Accepted Answer · answered Jun 03 '11 at 09:55

You can't apply the _TEXT macro twice. or on multiple strings, but you can concatenate the results. I.e.

#define LOG_FILENAME _TEXT(NAME_PART1) _TEXT(NAME_PART2) _TEXT(".log")

However, you really shouldn't bother. The _TEXT macro was used around the turn of the century, when there were still non-Unicode platforms around. Today we just write #define NAME_PART1 L"VenorBlaBla" ; nobody is selling Windows 95 software anymore.

score 1 · Answer 2 · answered Jun 03 '11 at 09:55

This is because the _TEXT is being applied to NAME_PART1 only, and not the other parts, this should be written as:

#define NAME_PART1 "VenorBlaBla"
#define NAME_PART2 "Driver"

#define LOG_FILENAME      _TEXT(NAME_PART1) _TEXT(NAME_PART2) _TEXT(".log")
#define REGISTRY_FILENAME _TEXT(NAME_PART1) _TEXT(NAME_PART2)
#define VENDOR_NAME       _TEXT(NAME_PART1)

The mismatch is _TEXT is defining a wide-string, where as the other strings are still normal strings.

score 1 · Answer 3 · answered Jun 03 '11 at 09:55

1

Wouldn't this work (not got a compiler to hand yet to try it out):

#define LOG_FILENAME _TEXT(NAME_PART1) _TEXT(NAME_PART2) _TEXT(".log")

and then let the compiler concatenate the two strings.

answered Jun 03 '11 at 09:55

Skizz

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"Define" Macro Concatenation and _TEXT

3 Answers3