(Solved Homework): Task Create a C++ application which wi read a file of daily payments, calculate the total as well as the average

* exception.h
*
* Created on: 02-Jun-2017
*      Author: Rj
*/

#ifndef EXCEPTION_H_
#define EXCEPTION_H_

#include <stdexcept>
using namespace std;

class Argc_error : public logic_error
{
public:
Argc_error(string);
};

class Readfile_error : public logic_error
{
public:
Readfile_error(string);
};

class Digit_error : public logic_error
{
public:
Digit_error(string);
};

class Writefile_error : public logic_error
{
public:
Writefile_error(string);
};

#endif /* EXCEPTION_H_ */

/*
* exception.cpp
*
* Created on: 02-Jun-2017
*      Author: Rj
*/

#include <string>
#include “exception.h”
using namespace std;

Argc_error::Argc_error(string m) : logic_error(m)
{}

Readfile_error::Readfile_error(string m) : logic_error(m)
{}

Digit_error::Digit_error(string m) : logic_error(m)
{}

Writefile_error::Writefile_error(string m) : logic_error(m)
{}

Here is the main file:

//============================================================================
// Name        : main.cpp
// Author      : Ramachandra jr
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include “exception.h”
#include <fstream>
#include <sstream>
#include <cmath>
using namespace std;

struct Payment
{
string _name;
int _payment;
string _comment;
};

const int MAX = 100;
// Payments array.
Payment *payments = new Payment[MAX]{};
int size = 0;

/**
* Reports any non numeric charaters in a string. Removes if just whitespace.
* @param {string} str – String to convert.
* @return {string} String with just numbers.
*/
string just_nums(string str)
{
string no_spaces = “”;
for (int i = 0; i < str.length(); ++i)
{
int dig = str.at(i)-48;

// If a space.
if ( dig == -16 )
{}
// 0 – 9
else if (dig > -1 && dig < 10)
no_spaces += str.at(i);
// non numeric
else
throw Digit_error(“There was a non character”);
}

return no_spaces;
}

/**
* Converts a legit number in string form to integer.
* @param {string} num – Number to convert to int.
* @return {int} Integer form of string.
*/
int str_to_int(string num)
{
const int LEN = num.length();
int tot = 0;

for (int i = 0; i < LEN; ++i)
tot += (num.at(i)-48) * pow(10,LEN-i-1);

return tot;
}

void extract_data(Payment *p1, string line)
{
stringstream ss(line);
int len = line.length();

char *name        = new char[41]{};
char *pay        = new char[11]{};
char *comment   = new char[len – 48]{};

ss.read(name, 40);
ss.read(pay, 10);
ss.read(comment, len – 49);

// char* to string
string pay_str(pay);

p1->_name = name;
try
{
pay_str = just_nums(pay_str);
p1->_payment = str_to_int(pay_str);
}
catch (Digit_error err)
{
throw Digit_error(err.what());
}
p1->_comment = comment;
}

Payment* open_file(const char *filename)
{
// file
fstream inf;
// For holding line.
string line;

// File handling.
inf.open(filename, ios_base::in);
if (! inf.is_open())
throw Readfile_error(“Unable to open file!”);

while(getline(inf, line))
{
Payment *p1 = new Payment{};
try {
extract_data(p1, line);
}
catch (Digit_error err)
{
cerr << “Error: ” << err.what() << endl;
continue;
}
payments[size] = *p1;
++size;
}

return payments;
}

int main(int argc, char *argv[]) {
Payment *pays;

try
{
// Improper arguments.
/*
* My IDE does not support command line args, you can go ahead and
* un comment lines below.
*/
//if (argc != 3)
//throw Argc_error(“Missing input / output filename(s)!”);

if (argv[1])
pays = open_file(argv[1]);
else
pays = open_file(“somefile.txt”);

for (int i = 0; i < size; ++i)
{
if (pays[i]._name.length() > 1) {
cout << i << “) “<< pays[i]._name
// To see if its addable.
<< ” – ” << pays[i]._payment
<< ” – ” << pays[i]._comment
<< endl;
}
}
}
catch (Argc_error err)
{
cerr << err.what() << endl;
cerr << “Usage: ./main <input_file> <output_file>”;
}

return 0;
}