And now the C++ approach. This is using Object Oriented idioms and modern C++ algorithms.
We have data and methods which belong somehow together. For this there are classes (structs) in C++. So you can define a class, with member variables and methods, which can work with the class varaibles. Everything works as one object.
Additionally. The class knows, how to read or print its values. And only the class should know that. This wisdom is encapsulated.
And, next, we want to search interesting data embedded somewhere in a string. The string contains always a certain pattern. In your case your have 3 integers and one string as interesting data and some delimiters in between, whatever they are.
To match such patterns and search for interesting parts of a string, C++ has std::regex. They are extremely powerful and hence a little bit complicated to define.
In the below example I will use const std::regex re(R"((\d+).*?(\d+).*?(\d+).*?([\w_]+))");. This defines 4 groups of submatches (in brackets) and something in between. So any delimiter, space or whatever is possible.
If you want to be more strict, you can simply change the pattern and you can detect errors in the source data. See const std::regex re(R"(\[(\d+)\,\ (\d+)\]\-(\d+)\-([\w_]+))");. This is a more strict approach. The inputfile will not be read in case of error. Or only the beginning with the valid data.
Please see below example:
#include <string>
#include <regex>
#include <iterator>
#include <iostream>
#include <sstream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <ios>
#include <iomanip>
std::istringstream testFile{ R"([1, 1]-3-Big_City
[1, 2] - 3 - Big_City
[1, 3] - 3 - Big_City
[2, 1] - 3 - Big_City
[2, 2] - 3 - Big_City
[2, 3] - 3 - Big_City
[2, 7] - 2 - Mid_City
[2, 8] - 2 - Mid_City
[3, 1] - 3 - Big_City
[3, 2] - 3 - Big_City
[3, 3] - 3 - Big_City
[3, 7] - 2 - Mid_City
[3, 8] - 2 - Mid_City
[7, 7] - 1 - Small_City)" };
const std::regex re(R"((\d+).*?(\d+).*?(\d+).*?([\w_]+))");
struct CityData
{
// Define the city's data
int xCoordinate{};
int yCoordinate{};
int cityId{};
std::string cityName{};
// Overload the extractor operator >> to read and parse a line
friend std::istream& operator >> (std::istream& is, CityData& cd) {
// We will read the line in this variable
std::string line{};
// Read the line and check, if it is OK
if (std::getline(is, line)) {
// Find the matched substrings
std::smatch sm{};
if (std::regex_search(line, sm, re)) {
// An convert them to students record
cd.xCoordinate = std::stoi(sm[1]);
cd.yCoordinate = std::stoi(sm[2]);
cd.cityId = std::stoi(sm[3]);
cd.cityName = sm[3];
}
else {
is.setstate(std::ios::failbit);
}
}
return is;
}
friend std::ostream& operator << (std::ostream& os, const CityData& cd) {
return os << cd.xCoordinate << ' ' << cd.yCoordinate << ' ' << cd.cityId;
}
};
constexpr int MinimumArrayDimension = 8;
int main()
{
// Define the variable cityData with the vectors range constructor. Read complete input file and parse data
std::vector<CityData> cityData{ std::istream_iterator<CityData>(testFile),std::istream_iterator<CityData>() };
// The following we are doing, because we want to print everything with the correct width
// Read the maximum x coordinate
const int maxRow = std::max(std::max_element (
cityData.begin(),
cityData.end(),
[](const CityData & cd1, const CityData & cd2) { return cd1.xCoordinate < cd2.xCoordinate; }
)->xCoordinate, MinimumArrayDimension);
// Read the maximum y coordinate
const unsigned int maxColumn = std::max(std::max_element(
cityData.begin(),
cityData.end(),
[](const CityData & cd1, const CityData & cd2) { return cd1.yCoordinate < cd2.yCoordinate; }
)-> yCoordinate, MinimumArrayDimension);
// Read the maximum city
const unsigned int maxCityID = std::max_element(
cityData.begin(),
cityData.end(),
[](const CityData & cd1, const CityData & cd2) { return cd1.cityId < cd2.cityId; }
)->cityId;
// Get the number of digits that we have here
const int digitSizeForRowNumber = maxRow > 0 ? (int)log10((double)maxRow) + 1 : 1;
const int digitSizeForColumnNumber = std::max(maxColumn > 0 ? (int)log10((double)maxColumn) + 1 : 1,
maxCityID > 0 ? (int)log10((double)maxCityID) + 1 : 1);
// Lambda function for printing the header and the footer
auto printHeaderFooter = [&]() {
std::cout << std::setw(digitSizeForColumnNumber) << "" << " #";
for (int i = 0; i <= (maxColumn+1)* (digitSizeForColumnNumber+1); ++i)
std::cout << '#';
std::cout << "#\n";
};
// Print the complete map
std::cout << "\n\n";
printHeaderFooter();
// Print all rows
for (int row = maxRow; row >= 0; --row) {
// Ptint the row number at the beginning of the line
std::cout << std::setw(digitSizeForColumnNumber) << row << " # ";
// Print all columns
for (int col = 0; col <= maxColumn; ++col)
{
// Find the City ID for the given row (y) and column (x)
std::vector<CityData>::iterator cdi = std::find_if(
cityData.begin(),
cityData.end(),
[row, col](const CityData & cd) { return cd.yCoordinate == row && cd.xCoordinate == col; }
);
// If we could find nothing
if (cdi == cityData.end()) {
// Print empty space
std::cout << std::setw(digitSizeForColumnNumber) << "" << ' ';
}
else {
// Print the CityID
std::cout << std::right << std::setw(digitSizeForColumnNumber) << cdi->cityId << ' ';
}
}
// Print the end of the line
std::cout << "#\n";
}
printHeaderFooter();
// Print the column numbers
std::cout << std::setw(digitSizeForColumnNumber) << "" << " ";
for (int col = 0; col <= maxColumn; ++col)
std::cout << std::right << std::setw(digitSizeForColumnNumber) << col << ' ' ;
// And, end
std::cout << "\n\n\n";
return 0;
}
Please note: main reads the file and displays the output.
And, because I cannot use file on SO, I read the data from "std::istringstream". This is the same as reading from a file.
