How do I point to an input stream?

Question

Im trying to use a pointer to point to my desired input stream depending on user decision. This is what ive got so far.

string fileName = "test.txt";
ifsteam = myFile;
myFile.open(fileName.c_str(), ifstream::in);
istream * myStream;    
if (file_mode) {
    myStream = &myFile;
} else {
    myStream = &cin;
}
string out;
while (myStream >> out) {
    cout << out << endl;
}

The problem seems to be that nothing is streaming from myStream to out.

Any help would be greatly appreciated.

Oh dear, how embarrassing, it seems that I forgot to include the file "text.txt" in the working directory. Some error checking would go far, my bad. — Tristus, May 18 '15 at 05:13

score 1 · Accepted Answer · answered May 18 '15 at 05:20

One problem is that 'myStream' is a pointer to istream, but in the while loop it is being used as an instance of istream. You need to deference the pointer for the code to work correctly. For instance:

while (*myStream >> out) {
    cout << out << endl;
}

How do I point to an input stream?

1 Answers1