How to sort string array by number if the string contains numbers and characters c++

Question

essentially i have a function that writes a score to a text file, however i'm not sure how to write to a respective line in the text file based on the score so it writes to the bottom of the file on the next available line, and i also want a function to print the top 10 scores, however since that file is not sorted by score ( if there's an easy way to do that instead an answer for that is welcome ) my idea was to read all the lines in the file and put them into an array of strings, and then sort the array based on the numbers inside the array.

for example, the text file has the format of SCORE then NAME, here is an example of the file

1548 Bob Jones
604 James Jones
5516 Example Name
24 Bad Score ikr

to print this to the file i get input for the name from user, then i output to file with

HighScore << totalScore << "  " << Name << std::endl;

i would like to be able to print the top 10 scores and the respective names of the player to the console, so the output would look something like this in the console

1) 5516 Example Name
2) 1548 Bob Jones
3) 604 James Jones
4) 24 Bad Score ikr

since my idea was to use arrays of strings, i still dont know how to sort it by the initial score numbers in the string, if there is a better solution to printing out the top 10 scores from a file then please let me know! thankyou

Answer 1

I suggest creating a class for keeping the score and name. You can then add operators for streaming objects of that class and a comparison operator. operator< is required by many standard functions and containers, so we'll add that. You can keep the scores you read in any container. I've used a std::set here which will keep the contents ordered at all times.

#include <algorithm> // std::copy, std::min
#include <iostream>  // std::cin, std::cout
#include <iterator>  // std::istream_iterator, std::ostream_iterator
#include <set>       // std::set
#include <sstream>   // std::istringstream
#include <string>    // std::string
#include <tuple>     // std::tie

class score_t {
public:
    bool operator<(const score_t& s) const {
        // sort on score in decending order
        // if scores are equal, sort on name, ascending order
        return std::tie(s.score, name) < std::tie(score, s.name);
    }

    friend std::istream& operator>>(std::istream& is, score_t& s) {
        if(is >> s.score) {
            is.ignore(1);             // ignore space between score and name
            std::getline(is, s.name); // read rest of line
        }
        return is;
    }

    friend std::ostream& operator<<(std::ostream& os, const score_t& s) {
        return os << s.score << ' ' << s.name;
    }

private:
    int score{};
    std::string name{};
};

int main() {
    // test data
    std::istringstream cin{
        "1548 Bob Jones\n"
        "604 James Jones\n"
        "5516 Example Name\n"
        "100 BBB\n"
        "100 AAA\n"
        "24 Bad Score ikr\n"};

    // Use the new operator>> to read score_t's from a stream and put them in a
    // set. std::set has a constructor taking iterators that can be used to populate the
    // set directly. Since cin is a stream and not an iterator, we can use
    // std::istream_iterator<score_t>(cin) to create an iterator to use as beginning.
    // std::istream_iterator<score_t>{} creates an end iterator. Read to the end of file.
    std::set<score_t> scores(std::istream_iterator<score_t>(cin),
                             std::istream_iterator<score_t>{});

    // print the top 5 of the collected score_t's
    // std::copy can copy a range of values given by iterators and insert them
    // where a third iterator points.
    // We copy from the beginning and then max 5 score_t's by creating the end
    // iterator using std::next. The result is copied to an ostream_iterator
    std::copy(scores.cbegin(),
              std::next(scores.cbegin(), std::min(scores.size(), 5ul)),
              std::ostream_iterator<score_t>(std::cout, "\n"));
}

Output:

5516 Example Name
1548 Bob Jones
604 James Jones
100 AAA
100 BBB

Answer 2

You can't use just one big string because 604 James Jones is lexicographically larger than 5516 Example Name. The first character of 604, 6, is greater than the 5 of 5516 in spite of 5516 being a larger number than 604.

Rather than an array of strings, I'd use a container, probably a std::vector, of a score structure. score would contain the score (possibly an int), the name (a string), and an operator< that could be used to arrange scores by their scores. Something like

struct score
{
    int mScore;
    std::string mName;
    bool operator<(const score & other)
    {
        return mScore < other.mScore;
    }
};

When parsing the file into the structure, use option 2 of this answer as inspiration.

You can then use std::sort from the algorithm library to sort the container.