How can I use C++ to write to an opened terminal? - c++

Question

I am trying to communicate with a program (xfoil) and read and write to its command line. Xfoil can take many parameters in its built in terminal.
I can open the program using system("path") but how do I input more commands to the opened xfoil terminal? Once I can do that I can do all that I need to do with the terminal commands.

Answer 1

Tiny Process Library is a good library for interacting with processes.
Checkout example 6 and 7 for giving commands to a process. https://gitlab.com/eidheim/tiny-process-library/blob/master/examples.cpp

Answer 2

How can I use C++ to write to an opened terminal
On linux, there are 7+ steps:
1) open a terminal
I find ctrl-alt t most convenient
press and hold ctrl and alt, then press t
There is also a selection LXTerminal on a mouse menu
Note - There is a way for your program to open a 'default' terminal,
and c++ can use the technique, but it is not c++, and I always seem to
need to change the defaults for my use.
2) using the terminal, you manually find the name of the terminal by:
type the command "tty" into the terminal
Typical response on my system:
hostname#username:~$ tty
/dev/pts/1
The terminal name is always of the form "/dev/pts/x" on my Linux system, where x is a number.
3) For my programs (that use a second terminal), my code accepts the x portion (of the terminal response) as command parameter 1, and uses that parameter to create a path file name (PFN) to the terminal.
std::string aTermPFN = "/dev/pts/"; // partial address
aTermPFN += argv[1]; // ouput tty identified by argv[1]
// creating /dev/pts/<argv[1]>
// thus creating PFN of "/dev/pts/1"
4) My code typically provides a confirmation of the number during creation. (recommended)
std::cout << "accessing '" << aTermPFN
<< "' with std::ofstream " << std::endl;
5) and then creates (or attempts to create) the ofstream object
std::ofstream* ansiTerm = new std::ofstream(aTermPFN);
6) and perform a few checks on it ...
if (!ansiTerm->is_open())
{
std::cerr << "Can not access '" << aTermPFN << "'" << std::endl;
assert(0); // abort
}
7) When done with term, be sure to clean up
ansiTerm->close();
delete ansiTerm;
// you can avoid the delete if you use an appropriate smart pointer.
Now all output to that 2nd terminal uses the 'ansiTerm' object, I happen to use a more generic term in that code (not a pointer, but reference) : "termRef".
Examples of use
// mostly, in the app where these sample exist, I output text at computed
// screen locations
// ansi terminals provide goto row col ansi functions
// the style is simply position the cursor,
termRef << m_ansi.gotoRC(3, col) << ss.str() << std::flush;
// then output text-----------------^^^^^^^^ (ss is stringstream)
// ansi terminals can clear
void clearScr() { termRef << m_ansi.clrscr() << std::flush; }
// ansi terminals can draw simple borders (not-fancy)
{ // across top gotoRC (int row, int col )
termRef << m_ansi.gotoRC ( tlcRow, tlcCol+1);
for ( int i=0; i<borderWidth; ++i) termRef << m_acs.HLINE;
termFlush();
}