I've looked around and I haven't found a good answer.
I have files like this: text1.txt text2.txt text3.txt
user wants to specify which file to open:
int x;
string filename;
cout << "What data file do you want to open? (enter an int between 1 -> 3): ";
cin >> x;
filename = "P3Data" << x << ".txt" ; //does not compile
myfile.open(filename);
What is the proper way to do this?
To use the streaming interface, you need a stringstream:
std::ostringstream filename;
filename << "P3Data" << x << ".txt";
myfile.open( filename.str().c_str() );
Otherwise, you can concatenate two strings using +.
In C++11, you can say it like this:
#include <string>
const std::string filename = std::string("P3Data") + std::to_string(x) + std::string(".txt");
If you don't have C++11, you can use boost::lexical_cast, or string streams, or snprintf. Alternatively, you could just read from std::cin into a string rather than an integer.
(If you read into an integer, surround the read with a conditional check to verify the operation: if (!(std::cin >> x)) { /* error! */ }
