Get FileName out of SaveDialog and change it dynamically c++ - c++-cli

Question

here is my problem:
I want to expand the FileName that the user gives the program in the SaveFileDialog with an index number.
I get the complete Path out of the dialog and search '.' in it.
System::String^ str = saveFileDialog1->FileName;
pin_ptr<const wchar_t> wch = PtrToStringChars(str);
size_t convertedChars = 0;
size_t sizeInBytes = ((str->Length + 1) * 2);
errno_t err = 0;
char *FileName = (char*)malloc(sizeInBytes);
err = wcstombs_s(&convertedChars,
FileName, sizeInBytes,
wch, sizeInBytes);
for (size_t i = 0; i < sizeof((*FileName )); i++)
{
if (FileName [i]=='.')
{
}
}
and at this point I have tried different things to edit the FileName with:
insert(i-1, ("_%i",i));
Nothing I have tried, works how I want it.
I want to save different pictures of a camera and with this index it is easier for the user to find the picture he want.
Thanks in advance!
Knut

Answer 1

So, you basically need to split filename to its raw name and extension, and then join these parts with some index. You can use this function:
string get_indexed_name(string filename, string index)
{
size_t lastindex = filename.find_last_of("."); // get position of dot
string rawname = filename.substr(0, lastindex); // get string contents before dot
string extension = filename.substr(lastindex + 1); // get string contents after dot
return rawname + index + "." + extension; // return indexed name
}
This way uses predefined standard functions. If you want to do (and learn) it yourself, try to implement functions find_last_of and substr. Then you can use your own implementation.
If there is some compilation problem, be sure to start your source code with these lines:
#include <iostream>
using namespace std;

Answer 2

Here is my Solution:
System::String^ str = saveFileDialog1->FileName;
std::string sFilePath = msclr::interop::marshal_as< std::string >(str);
std::string fileExtension=msclr::interop::marshal_as< std::string >(str);
size_t pos= sFilePath.find('.', 1);
sFilePath = sFilePath.substr(0, pos );
fileExtension = fileExtension.substr(pos);
for(size_t i=0; i<100; i++){
std::string fileName;
fileName = sFilePath + std::to_string(i) + fileExtension;}
For this solution you have to include.
#include <msclr\marshal_cppstd.h>
And if you want that your file number is with leaded zeros you have to use
stringstream like this:
string fileName;
string fileNumber ;
stringstream ss;
ss <<'_'<< setfill('0') << setw(4) << std::to_string(i);
fileNumber = ss.str();
fileName = f_sFilePath + fileNumber + f_sFileExtension;