Question

I’m trying to write an mpi program where each node knows its own rank, which is an integer.

I this program I hope each node to create a .txt file with its rank as the file name. That is, I hope the program to generate a file called rank.txt where rank is an integer.

I know how to convert an int to string, but I am quite confused about how I can combine that string with .txt and put it into a filename. What is the easiest way to do it?

Thanks in advance.

EDIT

I have combined the number with .txt and put them into a string filename but when I typed std::ofstream out_stream(filename) the compiler tells me that

no matching constructor for initialization `std::outstream`

How can I put the string into a filename?

Answer 1

The problem is that there’s no constructor for std::ofstream that takes a std::string. You need to pass const char*, so just say:

std::ofstream out_stream(filename.c_str());

Things have changed with the latest standard revision, though, so check your compiler documentation for how to enable C++11.