how to write and read points to binary file?

Question

I've programmed a code in C++ of a ball that moves in the space (3D points). I have all its movements positions. I mean, all the path points it passed.

I have to write its all positions\points into a binary file and then read it in order to restore the movements\path. for example, if I move the ball up and right, I'll want to save all the positions it passed so then I can read them and draw the ball moves the same, restore its path.

I saw an example for binary file but it doesn't say much to me:

 // reading a complete binary file
 #include <iostream>
 #include <fstream>
 using namespace std;

 ifstream::pos_type size;
 char * memblock;

 int main () {
   ifstream file ("example.bin", ios::in|ios::binary|ios::ate);
   if (file.is_open())
   {
     size = file.tellg();
     memblock = new char [size];
     file.seekg (0, ios::beg);
     file.read (memblock, size);
     file.close();

     cout << "the complete file content is in memory";

     delete[] memblock;
   }
   else cout << "Unable to open file";
   return 0;
 }

Does it create the file automatically? Then where? And what about writing and reading points (X,Y,Z) ? Should I write it through binary bytes? or as points and the file makes it binary..?

Why do you want to read and write into binary file? Why not text format? — herolover
– herolover, Commented Jul 25, 2013 at 11:54
Your example just reads a file into memory with no interpretation of what the file actually contains and no example of writing the file. Keep Googling - there are plenty of examples out there... — John3136
– John3136, Commented Jul 25, 2013 at 11:56
herolover, I want to implement it in a function that is called each frame(Update function) so I don't need a big file but small. and John3136, I keep googling (: — Maor Cohen
– Maor Cohen, Commented Jul 25, 2013 at 12:00
But text format is human readable and better for debug. Are your points floating? If points are integer then memory overhead is not large. — herolover
– herolover, Commented Jul 25, 2013 at 12:07

cpp · Accepted Answer · 2013-07-25 12:18:41Z

1

You can write a point (X,Y,Z) to a binary file separating coordinates e.g by colons, and points by semicolons:

int X=10, Y=12, Z=13;
ofstream outfile("points.bin", ios::binary);
if (!outfile)
    cerr << "Could not open a file" << endl;
else
    outfile << X << ','
            << Y << ','
            << Z << ';';

answered Jul 25, 2013 at 12:18

cpp

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