CODEWITHSUNDEEP
c++parsingifstreamgetlineistringstream
user3455638
user3455638

Reputation: 609

Undefined characters while reading the file content without new line at the end of file

File (settings.txt) to parse:

FULLSCREEN=On
V_SYNC=On [no "\n" at the end of file]

In case with no ENTER "\n" output is:

MapKey= FULLSCREEN      MapValue= On
MapKey= V_SYNC  MapValue= Onřřřř

With ENTER "\n" at the end of file output is correct (without "řřřř"):

MapKey= FULLSCREEN      MapValue= On
MapKey= V_SYNC  MapValue= On

How to change the program to work without adding new line at the end of file? Code:

#include<iostream>
#include<fstream>
#include<sstream>
#include<vector>
#include<cstdint>
#include<memory>


int main()
{
    std::vector<std::pair<std::string, std::string>> container;
    std::ifstream containerFile("settings.txt", std::ifstream::binary);
    containerFile.seekg(0, containerFile.end);
    std::uint64_t fileSize = containerFile.tellg();
    containerFile.seekg(0);
    std::unique_ptr<char> fileBuffer(new char[fileSize]);
    containerFile.read(fileBuffer.get(), fileSize);

    std::istringstream fileContent(fileBuffer.get());
    std::string fileLine;
    while (std::getline(fileContent, fileLine))
    {
        std::istringstream bufferLine(fileLine);
        std::string option;
        if (std::getline(bufferLine, option, '='))
        {
            std::string value;
            if (std::getline(bufferLine, value))
            {
                container.emplace_back(make_pair(option, value));
            }
        }
    }
    for (auto &element : container)
    {
        std::cout << "MapKey= " << element.first << "   MapValue= " << element.second << std::endl;
    }
    containerFile.close();
}

Upvotes: 4

Views: 320

Answers (1)

arturx64
arturx64

Reputation: 953

You can rewrite your code in this way: 

std::vector<std::pair<std::string, std::string>> container;
std::ifstream containerFile("settings.txt");
containerFile.seekg(0, containerFile.end );
std::uint64_t fileSize = containerFile.tellg();
containerFile.seekg(0);

/* Changed code. Begin*/
containerFile >> std::noskipws;
std::vector<char> buffer;
buffer.reserve(fileSize);
std::copy(std::istream_iterator<char>(containerFile), std::istream_iterator<char>(), std::back_inserter(buffer));
buffer.push_back('\0');
std::istringstream fileContent(&buffer.front());
/* Changed code. End*/

std::string fileLine;
while (std::getline(fileContent, fileLine))
{
    std::istringstream bufferLine(fileLine);
    std::string option;
    if (std::getline(bufferLine, option, '='))
    {
        std::string value;
        if (std::getline(bufferLine, value))
        {
            container.emplace_back(make_pair(option, value));
        }
    }
}
for (auto &element : container)
{
    std::cout << "MapKey= " << element.first << "   MapValue= " << element.second << std::endl;
}
containerFile.close();

First of all you have to use the next flag: containerFile >> std::noskipws; It allows you to use whitespaces. Tab spaces, carriage returns and blank spaces are all considered whitespaces according to documentation.

Correct string representation requires Null character in the end, so the next line buffer.push_back('\0'); adds '\0' to the end of the buffer.

Upvotes: 1

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