Outfile causes crashes with a memory violation [closed] - c++

Question

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 5 years ago.
Improve this question
I am writing a program to convert numbers from decimal to binary. I already have the algorithm correct for it and the program works fine while using cout. However, as soon as I use outfile in my loop the program crashes with error code (0xC0000005).
Here is my source code:
#include <iostream>
#include <iomanip>
#include <fstream>
#include <cmath>
using namespace std;
int main()
{
int num, remainder_count;
ifstream infile; //define new input file stream
ofstream outfile; //define new output file stream
infile.open("C:\\Users\\Arctic-Gaming\\CLionProjects\\working\\Source\\Binary Conversion (Loop w File)\\Binary Input.txt"); //connect the stream to an actual file
if (!infile)
{
cout << "Cannot open input file! Program aborted" << endl;
return 1;
}
outfile.open("C:\\Users\\Arctic-Gaming\\CLionProjects\\working\\Source\\Binary Conversion (Loop w File)\\Decimal Output.txt"); //connect the stream to an actual file
do
{
int remainder [15] = {0};
remainder_count = 15;
infile >> num;
outfile << "\n" << num << endl;
if (num > 0 && num <= 65535)
{
while (num > 0)
{
remainder[remainder_count] = num % 2;
num /= 2;
remainder_count--;
}
remainder_count = 0;
while (remainder_count < 16)
{
if (remainder_count % 4 == 0)
{
outfile << " ";
}
outfile << remainder[remainder_count];
remainder_count++;
}
}
else if (num == 0)
outfile << "0000 0000 0000 0000" << endl;
else
cout << "Error! Invalid Input." << endl;
}
while (!infile.eof());
}

Answer 1

Your program has undefined behavior by accessing an element out-of-bounds. Since the behavior is undefined, the issue really has nothing to do with using std::cout as opposed to using file streams.
int remainder [15] = {0};
//...
remainder_count = 15;
//...
remainder[remainder_count] = num % 2; // out-of-bounds access (remainder[15] is out-of-bounds)
Once that line above is executed, all bets are off as to how your program will behave. The valid indices of an array range from 0 to n-1, where n is the number of elements in the array. So the valid indices are 0, 1, 2, up to 14 for the remainder array.
If you had switched to using std::array instead of regular C++ arrays, instead of undefined behavior, you would get an std::out_of_range exception thrown as soon as you access that element using at().
std::array<int, 15> remainder= {{0}};
remainder_count = 15;
//...
if (num > 0 && num <= 65535)
{
while (num > 0)
{
remainder.at(remainder_count) = num % 2; //... exception thrown
Live Example
So as you see, your program never "ran fine" as you claimed, and you will have to fix your program so that you are not going out-of-bounds of your array.