Luther Systems | Virtual On-site | tail -n command implementation

Anonymous User

In a language of your choice write a function that is equivalent to calling the command tail -n, N for an arbitrary integer N, only using the standard library.

I used C++ for this question and it was really messy. I would very much like to know if there is an elegant way to do this.

Here is my solution(I assumed the value of n as 10):

#include<iostream>
#include<fstream>
#include<string>

using namespace std;

class File
{ 
    private:  string fileName; 
              ifstream file; 
    public: File(string fname)
             {
                fileName = fname;
             }
            void openFile();
            void closeFile();
            int countlines();
            void printlines();
};

void File::openFile()
{
    file.open(fileName.c_str());
    if (!file)
	{
	    cout << "File not opening!" << endl;
    }
}

void File::closeFile()
{
     file.close();
}

int File::countlines()
{
    int lineCount = 0;
    string str;

    if (file)
       {
	        while (getline(file, str))
			{
                lineCount += 1;
            }
     }
   return lineCount;
}

void File::printlines()
{
    int lineCount = 0;
    string line;

    if (file)
	{
	    lineCount = countlines();

        file.clear();
        file.seekg(ios::beg);

        if (lineCount <= 10)
		{
		     while (getline(file, line))
			 {
			     cout << line << endl;
             }
        }
        else
        {
            int position = lineCount - 10;
            while (position--)
            {
                getline(file, line);
            }
           while (getline(file, line))
           {
               cout << line << endl;
           }
       }
}
}

int main()
{
cout << "Enter your file name: ";
cin >> fileName;

File file(fileName);
file.openFile();
file.printlines();
file.closeFile();

return 0;
}

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