How to input multiple values from a txt file into an array C++

Question

I am looking to input individual inputs of a .txt file into my array where each input is separated by a space. Then cout these inputs. How do I input multiple values from the .txt file into my array?

    int main()
{
    float tempTable[10];

    ifstream input;
    input.open("temperature.txt");

    for (int i = 0; i < 10; i++)
    {
        input >> tempTable[i];
        cout << tempTable[i];
    }

    input.close();

    return 0;
}

With what I have written here I would expect an input of the file to go according to plan with each value entering tempTable[i] however when run the program out puts extreme numbers, i.e -1.3e9.

The temperature.txt file is as follows:

25 20 11.2 30 12.5 3.5 10 13

How do I input multiple values from the .txt file into my array? Looks like you are already doing that. What is is doing that you don't expect? — drescherjm
– drescherjm, Commented Dec 1, 2019 at 16:44
If this is not working at all maybe you put your text file in the wrong location or named it differently than you thought. — drescherjm
– drescherjm, Commented Dec 1, 2019 at 16:47
Your code does not check or care if your file was actually read or if it contains enough values. I expect your file was not read at all. — drescherjm
– drescherjm, Commented Dec 1, 2019 at 16:48

SHR · Accepted Answer · 2019-12-02 12:42:15Z

1

Your file contains 8 elements, you iterate 10 times.

You should use vector or list and iterate while(succeded)

#include <vector>
#include <fstream>
#include <iostream>
int main()
{
    float temp;    
    std::ifstream input;
    input.open("temperature.txt");
    std::vector<float> tempTable;
    while (input >> temp)
    {
        tempTable.push_back(temp);
        //print last element of vector: (with a space!)
        std::cout << *tempTable.rbegin()<< " ";
    }
    input.close();
    return 0;
}

edited Dec 2, 2019 at 12:42

answered Dec 1, 2019 at 16:53

SHR

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Comments

camp0 · Accepted Answer · 2019-12-01 16:47:39Z

0

You can use boost::split or directly assing the descriptor to variables

std::ifstream infile("file.txt");

while (infile >> value1 >> value2 >> value3) {
    // process value1, value2, ....
}

Or use the other version

std::vector<std::string> items;
std::string line;

while (std::getline(infile, line)) {
    boost::split(items, line, boost::is_any_of(" "));
    // process the items
}

answered Dec 1, 2019 at 16:47

camp0

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