My file is not being copied correctly - c++

Question

I am new to c++ and kind of learned on my own, so I have a program that is supposed to read in the specified file from a file path and in theory make an exact copy. My issue is that I am always off (as in off by bytes, Ex, a 173 kb file is 177kb), and from what I am seeing the bigger the file the more I'm off. So why I am I wrong and is there a better way to do it?
int main()
{
//I was monitering memory usage, some reason if i wrote to console to fast, I couldn't moniter memory
system("pause");
ifstream inputFile;
inputFile.open("C:\\Users\\Tallennar\\Documents\\Tables.docx", ios::in | ios::binary);
ofstream outputFile;
outputFile.open("word.docx", ios::binary);
char buffer[257] = { ' ' };//one extra for \0
if (!inputFile)
printf("failed to open input file");
if (!outputFile)
printf("failed to open outputfile \n");
//gets my file size
inputFile.seekg(0, ios::end);
size_t fileSize = inputFile.tellg();
inputFile.seekg(0, ios::beg);
//some math to see how many times I need to loop
int leftOverFromIterations = fileSize % 256;
int fileSizeIterations = (fileSize - leftOverFromIterations) / 256;
int bufferSize = sizeof(buffer);
//loops through to print to output file
for (int i = 0; i <= fileSizeIterations; i++)
{
inputFile.read(buffer, bufferSize);
//so i dont get funny chars
buffer[256] = '\0';
outputFile.write(buffer, bufferSize);
//for me to see what is getting printed
std::cout << buffer;
}
//since not every file is divisible by 256, get the
// leftovers from the above for loop
inputFile.read(buffer, leftOverFromIterations);
//close files
inputFile.close();
outputFile.close();
system("pause");
return 0;
}

Answer 1

Several problems:
The for loop is running too many times, it should use i < fileSizeIterations.
You're overwriting the last character of the buffer with \0. You should set bufferSize to 1 less than the size of the array, so you don't read into the character needed for the null. Or you should use std::string instead of a C-style string.
You're not copying the leftovers to the output file.
You should also avoid hard-coding 256 throughout the code, and use bufferSize there.
int main()
{
//I was monitering memory usage, some reason if i wrote to console to fast, I couldn't moniter memory
system("pause");
ifstream inputFile;
inputFile.open("C:\\Users\\Tallennar\\Documents\\Tables.docx", ios::in | ios::binary);
ofstream outputFile;
outputFile.open("word.docx", ios::binary);
char buffer[257] = { ' ' };//one extra for \0
if (!inputFile)
printf("failed to open input file");
if (!outputFile)
printf("failed to open outputfile \n");
//gets my file size
inputFile.seekg(0, ios::end);
size_t fileSize = inputFile.tellg();
inputFile.seekg(0, ios::beg);
int bufferSize = sizeof(buffer)-1;
//some math to see how many times I need to loop
int leftOverFromIterations = fileSize % bufferSize;
int fileSizeIterations = (fileSize - leftOverFromIterations) / bufferSize;
//loops through to print to output file
for (int i = 0; i < fileSizeIterations; i++)
{
inputFile.read(buffer, bufferSize);
//so i dont get funny chars
buffer[bufferSize] = '\0';
outputFile.write(buffer, bufferSize);
//for me to see what is getting printed
std::cout << buffer;
}
//since not every file is divisible by bufferSize, get the
// leftovers from the above for loop
inputFile.read(buffer, leftOverFromIterations);
//so i dont get funny chars
buffer[leftOverFromIterations] = '\0';
outputFile.write(buffer, leftOverFromIterations);
//for me to see what is getting printed
std::cout << buffer;
//close files
inputFile.close();
outputFile.close();
system("pause");
return 0;
}

Answer 2

Why not use getline() instead? A lot less confusing.
int main()
{
//I was monitering memory usage, some reason if i wrote to console to fast, I couldn't moniter memory
system("pause");
ifstream inputFile;
inputFile.open("C:\\Users\\Tallennar\\Documents\\Tables.docx", ios::in | ios::binary);
ofstream outputFile;
outputFile.open("word.docx", ios::binary);
if (!inputFile)
{
printf("failed to open input file");
return 0; //if you didn't open the file don't continue
}
if (!outputFile)
{
printf("failed to open outputfile \n");
return 0; //if you didn't open the file don't continue
}
string line;
while(getline(inputFile, line ))
{
outputFile << line;
}
inputFile.close();
outputFile.close();
system("pause");
return 0;
}
Note: I added return 0; to your if statements so it stops if it can't open the files.
Disclaimer: I have not run this code as I do not have a compiler that can deal with files off hand.