Simple binary file IO

[Proqrammer]

Hi there,

Can anyone give me a very simple example of how to write a string of characters into a binary file?

Thanks.

[horace1]

Hi there,

Can anyone give me a very simple example of how to write a string of characters into a binary file?

Thanks.

have a look at the example in
http://www.cplusplus.c om/reference/clibrary/cstdio/fwrite.html

[DumRat]

Hi there,

Can anyone give me a very simple example of how to write a string of characters into a binary file?

Thanks.

You have to open the file in binary mode.

ofstream out;
out.open(im_out, ios::out|ios::binary);

here's something I did for my own amusement a while back.
Skip the main function.
Look for the "ofstream out" object in the functions. Hope u will get some idea.
This code is full of bugs I think.

#include <iostream.h>
#include <fstream>
#include <string>
#include <stdlib.h>
#include <sys/stat.h>
#include <math.h>
#include <windows.h>

using namespace std;

void Encrypt();
void Decrypt();

int main(int argc, char* argv[])
{
	while(true){
		system("cls");
		cout << "1. Encrypt" << endl;
		cout << "2. Decrypt" << endl;
		cout << "3. Exit" << endl;

		int choice;
		cout << endl << "Enter choice : " ;

		cin >> choice;

		if(choice == 1)
			Encrypt();
		else if(choice == 2)
			Decrypt();
		else
			exit(0);
	}

		return 0;
}

void Encrypt()
{

	ifstream in_image;
	ifstream in_file;
	ofstream out;

	system("cls");

	char* im_in = new char[200];
	char* f_in = new char[200];
	char* im_out = new char[200];

	cout << "Enter input image file(.tga) : " ;
	cin >> im_in;
	cout << "Enter input file : " ;
	cin >> f_in;
	cout << "Enter output file : " ;
	cin >> im_out;

	in_image.open(im_in, ios::in|ios::binary);
	in_file.open(f_in, ios::in|ios::binary);
	out.open(im_out, ios::out|ios::binary);

//	struct stat results;
//	if(stat(f_in, &results) != 0)
//	{	
//		cout << "Error opening input file!" << endl;
//		exit(1);
//	}
	
	delete im_in;
	delete im_out;
	delete f_in;

	int i, j, k;

	char* image_header = new char[54];
	char* image_buffer = new char[16];
	char* file_in_buffer = new char[1];
	char temp;

	int *bits = new int[8];				//Array to keep the bits in a byte.

	int operand; 

	in_image.read(image_header, 54);
	
	int f_length = 0;

	image_header[5] = (char)f_length%256;	
	image_header[6] = (char)(f_length/256)%256;
	image_header[7] = (char)(f_length/256)/256;

	out.write(image_header, 54);

	i = 0;

	do
	{
		in_image.read(image_buffer, 16);
		in_file.read(file_in_buffer, 1);
		
		if(in_file)
		{
			operand = 1;

			for(j = 0; j <8; j++)
			{
				if((file_in_buffer[0] & operand) != 0)	//Copying the file_in_buffer to the array.
					bits[j] = 1;
				else
					bits[j] = 0;
				operand = operand << 1;
			}
			
			k=0;

			for(j = 0; j < 16; j++)
			{
				if(j%4 == 0 || j%4 == 1)
				{
					image_buffer[j] = image_buffer[j] & (-2);		//Making the last bit 0.
					image_buffer[j] = image_buffer[j] ^ bits[k];
					k++;
				}
			}
		}

		out.write(image_buffer, 16);
		i++;

	}while(in_image);

	in_image.close();
	in_file.close();
	out.close();

	delete image_header;
	delete image_buffer;
	delete file_in_buffer;
	delete bits;
}	

void Decrypt()
{
	system("cls");

	ifstream image;
	ofstream out;

	char* im_in = new char[200];
	char* f_out = new char[200];

	cout << "Enter input image file(.tga) : " ;
	cin >> im_in;
	cout << "Enter output file : " ;
	cin >> f_out;

	image.open(im_in, ios::in | ios::binary);
	out.open(f_out, ios::out|ios::binary);

	delete im_in;
	delete f_out;

	char image_header[54];
	char image_buffer[16];
	char* temp = new char[1];
	int tempi;

	int bits[8];
	int i, j, k;

	int operand;

	image.read(image_header, 54);
	int f_length = 0;

	for(i = 0; i <1; i ++)
	{
		if(image_header[i+5] > -1)
			f_length += image_header[i+5]*pow(256, i); 
		else
			f_length += (256 + image_header[i+5])*pow(256, i);
	}


	i = 0;
	for(i = 0; i < f_length; i++)
	{
		
		for(j = 0; j < 8; j++)
		{
			bits[j] = 0;
		}
		
		image.read(image_buffer, 16);
		
				
		k = 0;
		
		for(j = 0; j <16; j++)
		{
			if(j%4 == 0 || j%4 == 1)
			{
				bits[k] = image_buffer[j] & 1;
				k++;
			}
			
		}

		tempi = 0;
		operand = 1;

		for(j = 0; j < 8; j++)
		{
			tempi += (bits[j]<<j) & operand;
			operand = operand << 1;
		}

		temp[0] = (char)tempi;

		out.write(temp, 1);

	
	}while(image);

	image.close();
	out.close();

	delete image_header;
	delete image_buffer;
//	delete temp;
}