C++ Pass a string into a pipe to gnuplot

Question

I'm having a small problem passing a string to gnuplot from c++ I can pass integers easily enough, but when I try a string (user defined as "title" earlier in the code):

fprintf(gnuplotPipe, "set title %s\n", title);

I get the error:

error: cannot pass objects of non-trivially-copyable type ‘std::string {aka class std::basic_string<char>}’ through ‘...’

So instead I tried using:

fprintf(gnuplotPipe, "set title %s\n", title.c_str());

and the code actually compiled, but when I ran it I got the error from Gnuplot:

line 0: undefined variable: h

Where "h" is just the test sting defined by "title".

Does anyone have any ideas on how to pass this?

Thanks in advance!

Answer 1

You have to put the title in quotes:

fprintf(gnuplotPipe, "set title \"%s\"\n", title.c_str());