如何从文件中读取数字并在数组中使用它们？

Question

I am making a program that asked the user to open and existing txt file. The program should read the numbers from the file and storing them into arrays. I am supposed to create different functions with those numbers in the array, such as getting the largest number, the lowest number, the sum, and the average. I have done the functions already but I do not know how to extract the numbers from the array.

Here is an example of numbers but instead of being separated by space, they're separated by a new line.

53 22 87 103 -3 75 220 1 64 543 98 44

int getLowest(int num[], int size);
int getHighest(int num[], int size);
int getSum(int num[], int size);
int getAverage(int num[], int size);

int main()
{
    string fileName;
    ifstream inputFile;
    const int ARRAY_SIZE = 12;
    int numbers[ARRAY_SIZE];

    cout << "Enter the name of imput file: ";
    cin >> fileName;

    inputFile.open(fileName);

    if (inputFile)
    {

            cout << " numbers read from input file.\n"
                << "The lowest value is " << getLowest(numbers, ARRAY_SIZE) << endl;
    }
    else
    {
        //Display error message
        cout << "Error, this file does not exist.";
    }
    system("pause");
}

int getLowest(int num[], int size)
{
    int temp = num[0];

    for (int i = 0; i < size; i++) 
    {        
        if (temp < num[i]) 
        {                 
            temp = num[i];
        }
    }
    return temp;
}

int getHighest(int num[], int size)
{
    int temp = num[0];

    for (int i = 0; i > size; i++)
    {
        if (temp > num[i])
        {
            temp = num[i];
        }
    }
    return temp;
}

int getSum(int num[], int size)
{
    int sum = 0;

    for (int i = 0; i < size; i++)
    {
        sum += num[i];
    }
    return sum;
}

double getAverage(int num[], int size)
{
    int sum = 0;
    double average;

    for (int i = 0; i < size; i++)
    {
        sum += num[i];
    }

    average = sum / size;

    return average;
}

When I open the file with the numbers shown above, the result I get does not work. I get:

010FFCE0 numbers read from input file. The lowest value is 1968178332

Where it says "010FFCE0" i would like to get something that says the numbers of values, and the lowest value I would like it to be the actual lowest value.

Answer 1

Here is an example of reading numbers from a file into std::vector<int> :

int number = 0;
std::vector<int>    database;
while (inputFile >> number)
{
  database.push_back(number);
}

The std::vector is a good choice here because it expands dynamically as necessary (performing dynamic memory allocation as necessary).

However, you don't need to store the numbers in order to determine the highest, lowest and average:

int sum = 0;
int highest;
int lowest;
inputFile >> highest;
lowest = highest;
sum = highest;
int number;
int quantity = 1;
while (inputFile >> number)
{
  if (number > highest)
  {
    highest = number;
  }
  if (number < lowest)
  {
    lowest = number;
  }
  sum += number;
  ++quantity;
}
double average = (sum * 1.0) / quantity;