Question

Objective:

Use input/output files, strings, and command line arguments.

Write a program that processes a text file by removing all blank lines (including lines that only contain white spaces), all spaces/tabs before the beginning of the line, and all spaces/tabs at the end of the line. The file must be saved under a different name with all the lines numbered and a single blank line added at the end of the file.

For example, if the input file is given as follows:

This is line 1

  
This is line 2

This is line 3   

Correct output:
1. This is line 1
2. This is line 2
3. This is line 3

The file names must be provided at the command line (see "Parsing command line arguments" below). To use your program, a user would type:

     ./a.out first.txt second.txt

Where "first.txt" is the input file name and "second.txt" is the output file name.

Your program must print usage/help message and quit if any of the following occurs:

• Wrong number of arguments at the command line.

• The input file fails to open

• The output file fails to open

• Your program must include, at least, the following functions:

• A function to display a usage message to the user.

• A function that removes all white spaces from the beginning and end of the line. Should

  take a string and return a string.

  Parsing command line arguments

  In C++ you can input data (in the form of strings) into your program on the command line (command line arguments). You can capture these data by adding two parameters to your main program as follows:
  int main (int argc, char *argv[])

  argc: (argument count) number of arguments on the line, including the name of the program

  argv: (argument vector) list of c-style strings that represent all the arguments including the name of the program.

  For example, executing the command:

       ./a.out file1.txt file2.txt
  

  Assigns:

       argc = 3
       argv[0] will be "./a.out"
       argv[1] will be "file1.txt"
       argv[2] will be "file2.txt"
  

  To get the file name into your program you would write the following code:

  string inputFileName = argv[1];
  string outputFileName = argv[2];
  

Answer 1

Please go threw code,comments and output.

#include <iostream>

#include <string>

#include <fstream>

using namespace std;

void removeWhightSpace(string file1, string file2) // remove blank line function

{

std::ifstream ifile(file1); // input file

std::ofstream ofile(file2); // output file

if (ifile.is_open()) { // open input file

std::string line; // take line to get file

while (getline(ifile, line)) { // get line from file

if(line == "" || line[0] == ' '|| line[0] == '\n') // check null or space in line

continue;

ofile << line << endl; // print line in output file

}

ifile.close(); // close input file

ofile.close(); // close output file

}

}

void usageMessage()

{

cout << "Usage: ./a.out file1.txt file2.txt" << endl;

}

int main(int argc, char * argv[]) // take argument from command line

{

if(argc != 3) // check argument and print message if wrong

{

usageMessage();

return 0;

}

string inputFileName = argv[1]; // take file from argument

string outFileName = argv[2];

removeWhightSpace(inputFileName, outFileName); // call white space function

}