Writing and reading in and from a binary file in c++ - c++

Question

I am a beginner in working with files. What I want to do in my code is to get a name from the user, and hide it in a .bmp picture. And also be able to get the name again from the file. But I want to change the characters into ASCII codes first ( that's what my assignment says)
What I tried to do is to change the name's characters to ASCII codes, and then add them to the end of the bmp picture which I'll open in binary mode. And after adding them, i want to read them from the file and be able to get the name again.
This is what I've done so far. But I am not getting a proper result. All i get is some meaningless characters. Is this code even right?
int main()
{
cout<<"Enter your name"<< endl;
char * Text= new char [20];
cin>> Text; // getting the name
int size=0;
int i=0;
while( Text[i] !='\0')
{
size++;
i++;
}
int * BText= new int [size];
for(int i=0; i<size; i++)
{
BText[i]= (int) Text[i]; // having the ASCII codes of the characters.
}
fstream MyFile;
MyFile.open("Picture.bmp, ios::in | ios::binary |ios::app");
MyFile.seekg (0, ios::end);
ifstream::pos_type End = MyFile.tellg(); //End shows the end of the file before adding anything
// adding each of the ASCII codes to the end of the file.
int j=0;
while(j<size)
{
MyFile.write(reinterpret_cast <const char *>(&BText[j]), sizeof BText[j]);
j++;
}
MyFile.close();
char * Text2= new char[size*8];
MyFile.open("Picture.bmp, ios:: in , ios:: binary");
// putting the pointer to the place where the main file ended and start reading from there.
MyFile.seekg(End);
MyFile.read(Text2,size*8);
cout<<Text2<<endl;
MyFile.close();
system("pause");
return 0;
}

Answer 1

Many flaws are in your code, one important is:
MyFile.open("Picture.bmp, ios::in | ios::binary |ios::app");
Must be
MyFile.open("Picture.bmp", ios::in | ios::binary |ios::app);
^ ^
| |
+-----------+
Second, use std::string instead of C-style strings:
char * Text= new char [20];
should be
std::string Text;
Also, use std::vector to make a array:
int * BText= new int [size];
should be
std::vector<int> BText(size);
And so on...

Answer 2

You write int (which is 32 bits) but read char (which is 8 bits).
Why not write the string as-is? There's no need to convert it to an integer array.
And also, you don't terminate the array you read into.

Answer 3

your write operation is incorrect, you should pass the complete text directly
MyFile.write(reinterpret_cast <const char *>(BText), sizeof (*BText));
Also, casting your string to ints and back to chars will insert spaces between your characters which you don't take into account in your reading operation