Division answer not executing properly - c++

Question

I am having trouble with the following line of code:
double answer;
answer = num[count] / den[count]
cout << " Fraction" << count + 1 << " " << num[count]
<< " / " << den[count] << " = " << answer << endl;
How come my rendition of answer is not working? Am I overlooking something? I am using arrays and am getting the data from a separate text file. When I use the code above I get the numbers that are to be divided correctly but the answer is incorrect. It comes out to be a random number usually 0 or 1.
Here is my code:
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
using namespace std;
void read_data(int num[], int den[], int size);
void showValues(int num[],int den[], int size);
int main()
{
const int size1 = 12;
const int size2 = 12;
ifstream dataIn;
int num[12];
int den[12];
read_data(num,den,size1);
cout << "Here are the fractions: " << endl;
showValues(num,den,size1);
system("PAUSE");
return 0;
}
void read_data(int num[], int den[], int size)
{
ifstream dataIn;
dataIn.open("walrus.txt");
if( dataIn.fail() )
{
cout << "File does not exist." << endl;
exit(1);
}
int count;
for ( count = 0; count < size; count++ )
{
dataIn >> num[count];
}
for (count = 0; count < size; count++)
{
dataIn >> den[count];
}
dataIn.close();
}
void showValues(int num[],int den[], int size)
{
int count;
for (count = 0; count < size; count++)
{
if (den[count] == 0)
{
cout << " Fraction" << count + 1 << " "
<< num[count] << " /" << den[count]
<< " Is invalid" << endl;
}
else
{
double answer;
answer = num[count] / den[count];
cout << " Fraction" << count + 1 << " "
<< num[count] << " / " << den[count]
<< " = " << answer << endl;
}
}
}

Answer 1

#main ifstream dataIn;
You are not using this object
#function read_data :
int count;
for ( count = 0; count < size; count++ )
{
dataIn >> num[count];
}
for (count = 0; count < size; count++)
{
dataIn >> den[count];
}
Assuming ur file looks like :
1 2 23 32 44 // numerators
2 3 1 99 24 // den
The proper way to read is :
int count = 0;
while( count < size && dataIn >> num[count++] ) // numerators
;
count = 0;
while( count < size && dataIn >> den[count++] )
;
#function showValues :
try changing
double answer;
answer = num[count] / den[count];
cout << " Fraction" << count + 1 << " "
<< num[count] << " / " << den[count]
<< " = " << answer << endl;
to :
double answer = static_cast<double>(num[count]) / den[count];
cout << " Fraction" << count + 1 << " "
<< num[count] << " / " << den[count] << " = " << answer << endl;

Answer 2

In C and C++, if you do,
double answer = 10 / 3;
your answer will be 3. The reason is you have 2 integers and an integer division will take place. The resulting output is then implicitly converted into a double. So the steps are,
double answer = 10 / 3
double answer = 3
double answer = 3.0
To fix this, you tell the compiler that you want this to be treated as floating point division.
double answer = 10.0 / 3;
This works by,
double answer = 10.0 / 3
double answer = 10.0 / 3.0
double answer = 3.33333333...
The compiler will implicitly cast the 3 into a larger double type, 3.0.
So in your code, you have to convert integer division into floating point division by casting at least one of the division arguments into a double.
double foo = num[count] / den[count];
simply becomes
double foo = num[count] / static_cast<double>(den[count]);
Alternatively, if one or both of the arrays were of double type, you would not have this problem requiring casts.