Exercise 9.3 (Completed)

1. (Practice) a. Create a file named test.dat containing the data in the test.dat file used in
Program 9.7. (You can use a text editor or copy the test.dat file from this book’s Web site.)

Done!!
test.dat contains the words "The grade was 92.5".

b. Enter and run Program 9.7 on your computer.

Done!!

2. (Modify) Rewrite Program 9.7 so that the origin for the seekg() method used in the for loop
is the start of the file rather than the end.

	for (offset = 0L; offset <= last; offset++)
	{
		inFile.seekg(offset, ios::beg);
		ch = inFile.get();
		cout << ch << " : ";
	}
	inFile.close();
	cout << endl;

3. (Modify) Modify Program 9.7 to display an error message if seekg() attempts to reference a
position beyond the end of file.

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
int main()
{
	string filename = "test.dat";
	char ch;
	long offset, last;
	ifstream inFile(filename.c_str());
	if (inFile.fail())   // check for successful open
	{
		cout << "\nThe file was not successfully opened"
			<< "\n Please check that the file currently exists"
			<< endl;
		exit(1);
	}
	inFile.seekg(0L, ios::end);   // move to the end of the file
	last = inFile.tellg();       // save the offset of the last character
	for (offset = 0L; offset <= last-1; offset++)
	{
		inFile.seekg(offset, ios::beg);
		ch = inFile.get();
		cout << ch << " : ";
		if (offset >= last){
			cout << "Error" << endl;
		}
	}
	inFile.close();
	cout << endl;
	system("PAUSE");
	return 0;
}

4. (Practice) Write a program that reads and displays every second character in a file named
test.dat.

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
int main()
{
	string filename = "test.dat";
	char ch;
	long offset, last;
	ifstream inFile(filename.c_str());
	if (inFile.fail())   // check for successful open
	{
		cout << "\nThe file was not successfully opened"
			<< "\n Please check that the file currently exists"
			<< endl;
		exit(1);
	}
	inFile.seekg(0L, ios::end);   // move to the end of the file
	last = inFile.tellg();       // save the offset of the last character
	for (offset = 0L; offset <= last - 1; offset++)
	{
		if (offset % 2 == 0){
		inFile.seekg(offset, ios::beg);
		ch = inFile.get();
		cout << ch << " ";
	   }
	}
	inFile.close();
	cout << endl;
	system("PAUSE");
	return 0;
}

5. (Practice) Using the seek() and tell() methods, write a function named fileChars()
that returns the total number of characters in a file.

double fileChars(){
	string filename = "test.dat";
	char ch;
	long offset, last;
	int total = 0;
	ifstream inFile(filename.c_str());
	inFile.seekg(0L, ios::end);   // move to the end of the file
	last = inFile.tellg();       // save the offset of the last character
	for (offset = 0L; offset <= last; offset++)
	{
		inFile.seekg(offset, ios::beg);
		ch = inFile.get();
		//cout << ch << " ";
		total =+ offset;
	}
	inFile.close();
	return total;
}


6. (Practice) a. Write a function named readBytes() that reads and displays n characters starting
from any position in a file. The function should accept three arguments: a file object name,
the offset of the first character to be read, and the number of characters to be read. (Note: The
prototype for readBytes() should be void readBytes(fstream&, long, int).)

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;



void readBytes(ofstream& fileOut, long value, int n){
	string filename = "test.dat";
	char ch;
	long last;
	int total = 0;
	ifstream inFile(filename.c_str());
	inFile.seekg(0L, ios::end);   // move to the end of the file
	last = inFile.tellg();       // save the offset of the last character
	for (long offset = value; offset <= value+n; offset++)
	{
		inFile.seekg(offset, ios::beg);
		ch = inFile.get();
		cout << ch << " ";
		
	}
	inFile.close();
	return;
}


int main()
{
	string filename = "test.dat";
	char ch;
	long offset, last;
	string file = "test1.dat";
	ifstream inFile(filename.c_str());
	ofstream fileOut(file.c_str());

	if (inFile.fail())   // check for successful open
	{
		cout << "\nThe file was not successfully opened"
			<< "\n Please check that the file currently exists"
			<< endl;
		exit(1);
	}

     readBytes(fileOut, 2L, 8L);
	system("PAUSE");
	return 0;
}

b. Modify the readBytes() function written in Exercise 6a to store the characters read into
a string or an array. The function should accept the storage address as a fourth argument.

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;

void readBytes(ofstream& fileOut, long value, int n){
	string filename = "test.dat";
	char ch;
	long last;
	int total = 0;
	ifstream inFile(filename.c_str());
	inFile.seekg(0L, ios::end);   // move to the end of the file
	last = inFile.tellg();       // save the offset of the last character
	for (long offset = value; offset <= value+n; offset++)
	{
		inFile.seekg(offset, ios::beg);
		ch = inFile.get();
		cout << ch << " ";
		fileOut << ch << " ";
		
	}
	inFile.close();
	return;
}

int main()
{
	string filename = "test.dat";
	char ch;
	long offset, last;
	string file = "test1.dat";
	ifstream inFile(filename.c_str());
	ofstream fileOut(file.c_str());

	if (inFile.fail())   // check for successful open
	{
		cout << "\nThe file was not successfully opened"
			<< "\n Please check that the file currently exists"
			<< endl;
		exit(1);
	}

    readBytes(fileOut, 2L, 8L);
	system("PAUSE");
	return 0;
}