Converting a string to an int

Question

I'm getting random numbers after running the line convert >> quarter, I figure I have to clear stringstream out before I run it to convert again, but how would I go about doing that? And could someone explain what's going on during: (I found this as a solution but don't quite understand it)

    stringstream convert(tokens[1]);
    convert >> quarter;

-

Play parse(string toParse){
    vector<string> tokens;
    string play = toParse;
    string oName, dName;
    int x, quarter, minutes, down, yardstogo, startloc, playdesc;
    for(int y=0; y<10; y++){
        x = toParse.find(",");
        tokens.push_back(toParse.substr(0,x));
        toParse = toParse.substr(x+1);
    }
    stringstream convert(tokens[1]);
    convert >> quarter;
    convert.str(tokens[2]);
    convert >> minutes;
    convert.str(tokens[6]);
    convert >> down;
    convert.str(tokens[7]);
    convert >> yardstogo;
    convert.str(tokens[8]);
    convert >> startloc;
    playdesc = findPlay(tokens[9]);
    Play a(quarter, minutes, tokens[4], tokens[5], down, yardstogo, startloc, playdesc, play);
    return a;
}

Thank you.

How to clear a stringstream (extremely searchable): http://stackoverflow.com/questions/20731/in-c-how-do-you-clear-a-stringstream-variable — chris, Sep 17 '13 at 00:43
You don't need to clear it because you're reinitializing it with `convert.str(...)`. — Barmar, Sep 17 '13 at 00:45
I was hoping for an explanation on top of that, Chris. Barmar, do you know what I would get bad values then? Quarter and minutes are both ints, when I convert the string of quarter to an int, it's successful, when I convert minutes, I get a very large number. — Will Nasby, Sep 17 '13 at 00:47

score 1 · Answer 1 · answered Sep 17 '13 at 01:15

If you keep doing it this way, you need to call clear() after calling str():

stringstream convert(tokens[1]);
convert >> quarter;                // Conversion 1
convert.str(tokens[2]);
convert.clear();
convert >> minutes;                // Conversion 2
...

The problem is that the first conversion reads the entire string, which means that it sets the iostate of the stream to eof. Calling str() does not reset the iostate. You have to do it manually.

In your code the iostate is eof on all the later conversions, so no conversion is even attempted.

score 0 · Answer 2 · answered Sep 17 '13 at 01:31

0

You should probably use the atoi() function wich is faster than the stringstream conversion method.

Like so:
quarter = atoi(tokens[1].c_str());
minutes = atoi(tokens[2].c_str());
...

Regards

answered Sep 17 '13 at 01:31

Oli_G

460
3
17

score 0 · Answer 3 · answered Sep 17 '13 at 06:20

0

You could just use the <string> function stoi (C++11)...

quarter = stoi(tokens[1])

answered Sep 17 '13 at 06:20

erlc

652
1
6
11

Converting a string to an int

3 Answers3