C++ Files.

[babaliaris]

Can someone tell me why the statement if( read.eof() ) is not executed?
I'm reading the whole file so this stream should reach the end of file, yet i
can't understand why the statement is not running.

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

int main(){
	
	std::ifstream read("Source.cpp", std::ios::binary |
		std::ios::ate);

	std::ofstream write("C:\\Users\\zervos\\Desktop\\s.cpp",
		std::ios::binary);

	std::streampos size;

	char *bytes;

	if (read.is_open() && write.is_open()) {

		size =  read.tellg();

		bytes = new char[size];

		read.seekg(0, std::ios::beg);

		read.read(bytes, size);

		if ( read.eof() )
			std::cout << "eof" << std::endl;

		read.close();

		write.write(bytes, size);

		delete[] bytes;

		write.close();

	}

	else
		std::cout << "Files error" << std::endl;
	
	system("pause");
	return 0;
}

[2kaud]

eof is true when the get pointer is at the eof and another read is done. It's not a status but an error condition. If you try this

		read.read(bytes, size);
		if (read.eof())
			std::cout << "eof1" << std::endl;

		read.read(bytes, 1);

		if (read.eof())
			std::cout << "eof2" << std::endl;

You'll find the eof2 is displayed, not eof1.

[babaliaris]

I searched how to read chunks of bytes from a file. Then i programmed this which is not working.
I'm trying to read a file byte to byte but my output file (at the end of the execution) is zero bytes while the original is 585 bytes
Obviously i did not understand something.

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

int main(){
	
	std::ifstream read("Source.cpp", std::ios::binary |
		std::ios::ate);

	std::ofstream write("C:\\Users\\zervos\\Desktop\\s.cpp",
		std::ios::binary);


	char *byte = new char;

	if (read.is_open() && write.is_open()) {

		while (1) {

			read.read(byte, 1);

			if (!read.gcount())
				break;

			write.write(byte, 1);
		}

		read.close();
		write.close();

		delete byte;
	}

	else
		std::cout << "Files error" << std::endl;
	
	system("pause");
	return 0;
}

These are really stupid questions, but i cant find a good documentation for c++ libraries. Also in visual studio when you select a method it doesn't showing you info about what the method does, but only the definition. If you can point me on a website that would be nice.

[babaliaris]

I searched how to read chunks of bytes from a file. Then i programmed this which is not working.
I'm trying to read a file byte to byte but my output file (at the end of the execution) is zero bytes while the original is 585 bytes
Obviously i did not understand something.

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

int main(){
	
	std::ifstream read("Source.cpp", std::ios::binary |
		std::ios::ate);

	std::ofstream write("C:\\Users\\zervos\\Desktop\\s.cpp",
		std::ios::binary);


	char *byte = new char;

	if (read.is_open() && write.is_open()) {

		while (1) {

			read.read(byte, 1);

			if (!read.gcount())
				break;

			write.write(byte, 1);
		}

		read.close();
		write.close();

		delete byte;
	}

	else
		std::cout << "Files error" << std::endl;
	
	system("pause");
	return 0;
}

These are really stupid questions, but i cant find a good documentation for c++ libraries. Also in visual studio when you select a method it doesn't showing you info about what the method does, but only the definition. If you can point me on a website that would be nice.

LOL sorry my bad, i forgot that: std::ifstream read("Source.cpp", std::ios::binary | std::ios::ate);

I start reading from the end of the file

[2kaud]

but i cant find a good documentation for c++ libraries

Have a look at http://www.cplusplus.com/reference/

Reading/writing a file in chucks is fairly easy. Consider

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

int main()
{
	const size_t bufsz = 20;

	ifstream read("data.txt", ios::binary);
	ofstream write("data4.txt", ios::binary);

	if (read.is_open() && write.is_open()) {
		char buf[bufsz];

		do {
			read.read(buf, bufsz);
			write.write(buf, read.gcount());
		} while (read.gcount());

		read.close();
		write.close();
	} else
		std::cout << "Files error" << std::endl;

	//system("pause");
	return 0;
}

which copies read to write using a buffer of size bufsz characters.