C++ - How to input space separated numbers into array?

Question

I have this file:

4
10 3 4 6

The first line declares how many numbers the second line has.I want to put the numbers of the second line in an array.So far i have been using this loop to automatically declare how many numbers the second line has and how many times to do the loop:

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>

using namespace std;

int main(){
    ifstream infile;
    infile.open("input.in");
    string kids;
    int x;
    int i;
    getline(infile,kids);
    cout << "The Number Of Kids Is " << kids << endl;
    istringstream buffer(kids);
    int kidss;
    buffer >> kidss;
    for(i=0;i<kidss;i++){
        infile >> x;
        cout << x << " ";
    }
    infile.close();
    return 0;
}

Now i want to do the same thing but instead of inputing the numbers in x i want to put them in an array and then display them as above.Thanks In Advance!

Use a std::vector and the push_back() function.

πάντα ῥεῖ
– πάντα ῥεῖ

2015-01-05 10:37:19 +00:00
Commented Jan 5, 2015 at 10:37 — πάντα ῥεῖ
– πάντα ῥεῖ, Commented Jan 5, 2015 at 10:37

Simon Gibbons · Accepted Answer · 2015-01-05 10:40:44Z

3

The best way of doing this would be with a std::vector these are variable length arrays in c++.

To use them in this case you would do

std::vector<int> array;
for( int i = 0 ; i < kidss ; ++i ) {
    infile >> x;
    array.push_back(x);
}

Then if you wanted to print them out again you would be able to do

for( int i = 0 ; i < array.size() ; ++i ) {
    std::cout << array[i] << " ";
}

edited Jan 5, 2015 at 10:40

answered Jan 5, 2015 at 10:35

Simon Gibbons

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3 Comments

πάντα ῥεῖ Over a year ago

I would better recommend the reference link I've put in my comment on the question.

Clifford Over a year ago

@πάνταῥεῖ : Answers are better than comments, answers in comments are not good SO practice, neither are link only answers, so as a link only answer in a comment, your "answer" has little to recommend it in the context of SO.

πάντα ῥεῖ Over a year ago

It wasn' an answer, but a comment.

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