How to "select" current directory? - c++

Question

I am writing a proportion calculator. At the beginning of the program, it loads a ascii text art picture from a .txt in the same folder.
Here is how I am doing it:
//Read picture
string line;
ifstream myfile("/Users/MYNAME/Desktop/MathScripts/Proportions/Value Finder/picture.txt");
if (myfile.is_open()) {
while (!myfile.eof()) {
getline(myfile, line);
cout << line << endl;
}
myfile.close();
} else cout << "Unable to load picture!!!" << endl;
//Finish reading txt
I heard how if the .txt is in the same folder, that you can just use the name and not have to say the directory. Meaning instead of
/Users/MYNAME/Desktop/MathScripts/Proportions/Value Finder/picture.txt
I could just use "picture.txt". That doesn't work for me, and I want the user to be able to move around the "Value Finder" folder without having to edit any code.
I am on Mac and I am using CodeRunner; anything odd?
Please do not tell me to make sure that picture.txt is in the same folder as my code. It is.

Answer 1

In order to open picture.txt without using a fully qualified path it has to reside in the current working directory. When an IDE launches an application it it sets the current working directory to the same one the application resides in. If picture.txt resides in a different directory than the application you will not be able to open it with just it's name. If you need to get the current working directory you can call getcwd like so.
char temp[MAXPATHLEN];
getcwd(temp, MAXPATHLEN);
If you want to allow the user to specify which directory picture.txt is in you can let them pass an argument on the command line. You can then create a fully qualified path with the supplied directory and the picture filename.
int main(int argc, const char **argv)
{
// Add some logic to see if the user passes a path as an argument
// and grab it. here we just assume it was passed on the command line.
const string user_path = arg[1];
//Read picture
string line;
ifstream myfile(user_path + "/picture.txt");
if (myfile.is_open())
{
while (!myfile.eof()) {
getline(myfile, line);
cout << line << endl;
}
myfile.close();
}
else
{
cout << "Unable to load picture!!!" << endl;
}
//Finish reading txt
return 0;
}
Now you can do something like this:
myapp "/user/USERNAME/Desktop/MathScripts/Proportions/Value Finder"
and it will look in that directory for the picture.txt file. (Quotes are required because there is a space in the pathname).
Note: You can call setcwd() to change the current working directory of the application.