How can I append an int to a tchar? - c++

Question

For testing purposes I would like each time I create a file name to add a number to it - the app I am testing has no user interface, and will likely create multiple files.
void somefunction()
{
static INT iFileNo = 0;
TCHAR tFileName[MAX_PATH] = L"c:/test/abcd.bmp";
iFileNo ++;
}
I would like to somehow append the iFileNo to the tFileName (to get something like abcd1.bmp, abcd2.bmp...)... How can I do that ?
Note: I am not using any string libraries
Minimal libraries... including
#include <STDLIB.H>
#include <STDIO.H>
#include <TCHAR.H>
Intended OS: Windows

Answer 1

You can make this hard, easy, or very easy. The middle of those would be something like:
void somefunction()
{
static unsigned int uiFileNo = 0;
static const WCHAR wSpec[] = L"c:/test/abcd%u.bmp";
WCHAR wFileName[MAX_PATH];
swprintf_s(wFileName, MAX_PATH, wSpec, uiFileNo++);
}
Uses swprintf_s, which would seem to fulfill your include-file restrictions (and assuming this is Windows, which your question seems to indicate).
Personally I's use std::wstring, but it appears you have reasons against it. Anyway, best of luck.

Answer 2

You've expressed a desire to not use any libraries. That's not a choice I would endorse, but since you asked...
The easiest way would be to decide on a fixed number of digits, with leading zeros. That makes the problem trivial. In this example I'm using two digits.
void somefunction()
{
static INT iFileNo = 0;
TCHAR tFileName[MAX_PATH] = L"c:/test/abcd00.bmp";
int iNumberOffset = 12;
if (iFileNo >= 100)
throw std::runtime_error("File number too large");
tFileName[iNumberOffset] += iFileNo / 10;
tFileName[iNumberOffset+1] += iFileNo % 10;
iFileNo ++;
}

Answer 3

You can use ostringstream:
std::ostringstream s;
s << "c:/test/abcd.bmp"
s << iFileNo++;
std::string filename = s.str();
If you want wide versions (as you're specifying L in your example) then use wstringstream and wstring.
If you really don't want to use a C++ library then you can use sprintf:
char filename[100];
sprint(filename, "c:/test/abcd.tmp-%d", iFileNo);
iFileNo++
You'll need to ensure that you buffer is big enough to hold the filename.
If you really don't want to use any libraries then Windows actually has it's own string formatting function, wsprintf which you can use instead of sprintf.