Reading data from file into an array

61,713

Solution 1

Hi I have compiled your code, with the .txt it runs well, without gives the strage numbers that you see. So probably you are opening a file that does not exists, or can not be red.

// This program reads data from a file into an array.

#include <iostream>
#include <fstream> // To use ifstream
#include <vector>
using namespace std;

int main()
{
    std::vector<int> numbers;
    ifstream inputFile("c.txt");        // Input file stream object

    // Check if exists and then open the file.
    if (inputFile.good()) {
        // Push items into a vector
        int current_number = 0;
        while (inputFile >> current_number){
            numbers.push_back(current_number);
        }

        // Close the file.
        inputFile.close();

        // Display the numbers read:
        cout << "The numbers are: ";
        for (int count = 0; count < numbers.size(); count++){
            cout << numbers[count] << " ";
        }

        cout << endl;
    }else {
        cout << "Error!";
        _exit(0);
    }

    return 0;
}

This snippet checks if the file exists, raises an error if not, and uses a vector(more suitable in c++)

Solution 2

Your file name has rtf as suffix. Does it contain any RTF info in it?

The error that I see in your code is that you are assuming ARRAY_SIZE number of ints were successfully read when you are printing the numbers.

Use:

// Display the numbers read:
cout << "Number of ints read: " << count << std::endl;
cout << "The numbers are: ";
for (int i = 0; i < count; i++){
    cout << numbers[i] << " ";
}

This will, most likely, reveal any problems in reading the data.

Solution 3

ARRAY_SIZE is the number of ints you allocated in the array; that is, it is the max number of ints.

count is the actual number of ints read from the file. So your final loop should go up to count since that is the number of actual data. So the loop that prints your data should be:

int i;
for (i = 0; i < count; ++i)
    cout << numbers[count] << " ";

Or you can walk a pointer:

int *start;

for (start = numbers; (numbers - start) < count; ++numbers)
    cout << *numbers << " ";

Also, I think the file extension should be "txt" rather than "rtf", but that doesn't make a difference.

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61,713
Dante
Author by

Dante

Updated on January 12, 2021

Comments

  • Dante
    Dante about 3 years

    The program output Should be:

    The numbers are: 101 102 103 104 105 106 107 108 108 110

    But my output is:

    The numbers are: 0 0 0 0 0 0 0 0 1606416272 32767

    This is my code:

    // This program reads data from a file into an array.
    
    #include <iostream>
    #include <fstream> // To use ifstream
    using namespace std;
    
    int main()
    {
        const int ARRAY_SIZE = 10; // Array size
        int numbers[ARRAY_SIZE];   // Array number with 10 elements
        int count = 0;             // Loop counter variable
        ifstream inputFile;        // Input file stream object
    
        // Open the file.
        inputFile.open("TenNumbers.rtf");
    
        // Read the numbers from the file into the array.
        while (count < ARRAY_SIZE && inputFile >> numbers[count]){
            count++;
        }
    
        // Close the file.
        inputFile.close();
    
        // Display the numbers read:
        cout << "The numbers are: ";
        for (count = 0; count < ARRAY_SIZE; count++){
            cout << numbers[count] << " ";
        }
    
        cout << endl;
    
        return 0;
    }
    

    This is the contents of the TenNumbers.rtf file I'm reading the data from:

    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    

    UPDATE 1: I tried using txt file but the results are similar.

    The numbers are: 0 0 0 0 0 0 0 0 1573448712 32767

    UPDATE 2: I found where the issue was. After running if (inputFile.good()) I found out the file was not getting opened.