C++ and Readline

[rplantz]

This is very cool. After reading very little of the info on readline, it was very simple to modify my program so that I could maintain a history of previously entered lines. The other thing I realized is that I can edit a line using the arrow keys instead of deleting characters and typing them over again.

I have to admit that my initial response to pianoboy3333's question was "dumb question" and I almost gave a response like thumper's. But I was a CS professor for 21 years, where I learned a lot from my students' "dumb questions." First, they asked things that I didn't even know about. (Such is the case here. I had never heard of readline before.) Second, I had to then learn about the topic in order to avoid embarrassing myself in front of an entire class of students. (Still did that a few times. )

Thanks for raising the question and for the responses.

[pianoboy3333]

#include <string>
#include <iostream>

int main()
{
   std::string line;
   while (std::getline(std::cin, line)) 
   {
      if (line == "quit") 
      {
         std::cout << "Bye\n";
         break;
      }
      else std::cout << "echo: " << line << '\n';
   }
}

Caveat: untested code.

This would have been my last resort, but with readline() you can also interact with things such as Ctrl-T to do something...

A fine example is at http://piano.juicemedia.tv/rlexample.cc
Compile it with `g++ rlexample.cc -o rlexample -lreadline'

[thumper]

None of the examples (above, or the example posted above) actually free the memory that readline allocates.

According to the man page readline mallocs the memory and it is up to the caller to free it. Make sure you do. Assigning it to a string does not free the memory.

[rplantz]

None of the examples (above, or the example posted above) actually free the memory that readline allocates.

According to the man page readline mallocs the memory and it is up to the caller to free it. Make sure you do. Assigning it to a string does not free the memory.

Thanks. I saw that later when I read more on the man page. I added the free() to my very simple example above.