Reading in from a txt file. Trouble parsing info

Question

I want to read in scores from a txt file. The scores are going into a struct.

struct playerScore
{
    char name[32];
    int score, difficulty;
    float time;
};

the text file looks like this

Seth 26.255 40 7

as one line, where each item is followed by a tab. (Name\t time\t score\t difficulty\n)

When I begin to read in the text, I don't know how to tell the program when to stop. The scores file could be any number of lines or score entries. This is what I have attempted.

hs.open("scores.txt", ios_base::in);
hs.seekg(0, hs.beg);


if (hs.is_open())
    {
        int currpos = 0;
        while (int(hs.tellg()) != int(hs.end));
        {
                hs>> inScore.name;
                hs >> inScore.time;
                hs >> inScore.score;
                hs >> inScore.difficulty;
                hs.ignore(INT_MAX, '\n');
                AllScores.push_back(inScore);
                currpos = (int)hs.tellg();
        }
    }

I'm trying to make a loop that will read in a line of code into a temp struct for the data, then push that struct into a vector of structs. Then update the currpos variable with the current location of the input pointer. However, the loop just gets stuck on the condition and freezes.

try replacing your while(...) with while(hs.good()) – Vasily Redkin Mar 20 '14 at 06:19 — Vasily Redkin, Mar 20 '14 at 06:19

score 1 · Accepted Answer · answered Mar 20 '14 at 06:10

There are a multitude of ways to do this, but the following is likely what you're looking for. Declare a free-operator for extracting a single-line definition of a player-score:

std::istream& operator >>(std::istream& inf, playerScore& ps)
{
    // read a single line.
    std::string line;
    if (std::getline(inf, line))
    {
        // use a string stream to parse line by line.
        std::istringstream iss(line);
        if (!(iss.getline(ps.name, sizeof(ps.name)/sizeof(*ps.name), '\t') &&
             (iss >> ps.time >> ps.score >> ps.difficulty)))
        {
            // fails to parse a full record. set the top-stream fail-bit.
            inf.setstate(std::ios::failbit);
        }
    }
    return inf;
}

With that, your read code can now do this:

std::istream_iterator<playerScore> hs_it(hs), hs_eof;
std::vector<playerScore> scores(hs_it, hs_eof);

Douman · Answer 2 · 2014-03-20T05:12:06.280

0

I dont think that you can just >> from your file. Do you think it will take everything till \t? :)

You can try to take for example token with strtok() I guess it can use '\t' to split string and take for each variable via this function needed part of string In case if it strtok() doesnt work that way i guess you can just copy till '\t' in sub-loop

edited Mar 20 '14 at 05:12

answered Mar 20 '14 at 05:06

Douman

66
7

score 0 · Answer 3 · answered Mar 20 '14 at 05:19

0

You can do like this

playerScore s1;

fstream file;
file.open("scores.txt", ios::in | ios::out);
while(!file.eof()) //For end of while loop
{
    file.read(s1, sizeof(playerScore));//read data in one structure.
    AllScores.push_back(s1);
}

answered Mar 20 '14 at 05:19

EmptyData

2,386
2
26
42

Whoever told you `while (!file.eof())` is the right way to do this, kindly [**tell them they're wrong.**](http://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-considered-wrong). Looping on `std::istream::eof` is quite literally wrong in 99.99% of the cases it is done. (and this isn't the 0.01% exception to that). Ask yourself. How do you know that `file.read()` *worked* before blindly assuming it did and pushing `s1` into the container? – WhozCraig Mar 20 '14 at 05:51

Reading in from a txt file. Trouble parsing info

3 Answers3