Fivefold output from istringstream

Question

I would like to outout each line after a certain substring is detected. Somehow I get a fivefold output for iss. Here's my code:

    //load all data from txt
        string data;
        std::ifstream infile("SavedData.txt");
        while (std::getline(infile, data)) {
            std::istringstream iss(data);
            string d;
            while (iss >> d) {
                //extract substring
                unsigned firstBracket = data.find("(");
                unsigned lastBracket = data.find(")");
                string coordSynth = data.substr(firstBracket + 1, lastBracket - firstBracket - 1);
                cout << coordSynth << endl;
            }
        }

The output right now is like:

0.0, 45.0, -390.0
0.0, 45.0, -390.0
0.0, 45.0, -390.0
0.0, 45.0, -390.0
0.0, 45.0, -390.0
0.0, 45.0, -314.3
0.0, 45.0, -314.3
0.0, 45.0, -314.3
0.0, 45.0, -314.3
0.0, 45.0, -314.3
etc.

Actually I just want

0.0, 45.0, -390.0
0.0, 45.0, -314.3
0.0, 45.0, -277.3
etc.

And no, in the txt file there aren't duplcates. This file looks like this:

0001(0.0, 45.0, -390.0).png 
0003(0.0, 45.0, -314.3).png 
0007(0.0, 45.0, -277.3).png (and so on...)

0001(0.0, 45.0, -390.0).png 0003(0.0, 45.0, -314.3).png 0007(0.0, 45.0, -277.3).png and so on — , Jul 19 '17 at 11:49
Please [edit] that into the question with some formatting so it is readable. — NathanOliver, Jul 19 '17 at 11:51
You're finding/outputting the parenthesized expression once for each successful invocation of `iss >> d`. What is the `while (iss >> d)` loop supposed to do? — G.M., Jul 19 '17 at 12:02
@G.M. in the `while(iss >> d)` loop I extract the substring from the string as the comment above says. — , Jul 19 '17 at 12:04
Yes but it means you get the substring far too often. See the answer by @NathanOliver. — G.M., Jul 19 '17 at 12:06

score 2 · Accepted Answer · answered Jul 19 '17 at 12:03

Your issue here is that

unsigned firstBracket = data.find("(");
unsigned lastBracket = data.find(")");
string coordSynth = data.substr(firstBracket + 1, lastBracket - firstBracket - 1);
cout << coordSynth << endl;

Which is the logic to get 0.0, 45.0, -390.0 from 0001(0.0, 45.0, -390.0).png is inside a while loop that you're not even doing anything with. That loop is going to execute 5 times for every line of input (because there are five "sub strings") so you get 5 outputs. All you need to do is get rid of the while loop since you're not doing anything with the individual strings contained in the line. That gives you something like

int main() 
{   
    std::string data;
    std::istringstream infile("0001(0.0, 45.0, -390.0).png\n0003(0.0, 45.0, -314.3).png\n0007(0.0, 45.0, -277.3).png\n");
    while (std::getline(infile, data)) {
        std::istringstream iss(data);
        std::string d;
        //extract substring
        unsigned firstBracket = data.find("(");
        unsigned lastBracket = data.find(")");
        std::string coordSynth = data.substr(firstBracket + 1, lastBracket - firstBracket - 1);
        std::cout << coordSynth << std::endl;
    }
}

Fivefold output from istringstream

1 Answers1