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.com/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;
}