creating dynamic array of string c++

Question

I am struct to a very basic question. I want to create dynamically an array of string in c++.

How can I do that ?

This is my attempt:

#include <iostream>
#include <string>
int main(){
    unsigned int wordsCollection = 6;
    unsigned int length = 6;

    std::string *collection = new std::string[wordsCollection];
    for(unsigned int i = 0; i < wordsCollection; ++i){
        std::cin>>wordsCollection[i];
    }
    return 0;    
}

But it giving the following error

error C2109: subscript requires array or pointer type

What's the error ?

And also if I'am getting input number from user, from std::cin can I create an array of that size statically ?

In the future please select your code block and use the {} button; this will make your code show up properly in the question. — Mark Ransom
– Mark Ransom, Commented Jan 20, 2012 at 22:27
You typed wordsCollection[i] instead of collection[i]. You can't use a size obtained dynamically (e.g. through std::cin) to create a static array. Also, the array is leaking since you never release it. — R. Martinho Fernandes
– R. Martinho Fernandes, Commented Jan 20, 2012 at 22:30

johnsyweb · Accepted Answer · 2012-01-20 22:42:28Z

11

You meant to type:

std::cin>>collection[i];

And you also need to delete[] collection (or you'll leak this memory).

It would be better use std::vector<std::string> collection; and avoid the raw pointer usage altogether:

#include <iterator>
#include <iostream>
#include <string>
#include <vector>

int main()
{
    const unsigned int wordsCollection = 6;

    std::vector<std::string> collection;
    std::string word;
    for (unsigned int i = 0; i < wordsCollection; ++i)
    {
        std::cin >> word;
        collection.push_back(word);
    }

    std::copy(collection.begin(),
              collection.end(),
              std::ostream_iterator<std::string>(std::cout, "\n"));
}

edited Jan 20, 2012 at 22:42

answered Jan 20, 2012 at 22:30

johnsyweb

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Comments

rerun · Accepted Answer · 2012-01-20 22:27:10Z

10

use std::vector<string> or std::list<string> over hand rolling it.

answered Jan 20, 2012 at 22:27

rerun

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4 Comments

cnicutar Over a year ago

But the real problem is that wordsCollection should be collection.

Abdul Samad Over a year ago

Oh my God how silly i am... Any how thanks... can you tell me the answer for my second question that can i create a static array of that

Lea Hayes Over a year ago

I agree, but if you choose to go ahead with new std::string do not forget to delete[] collection when you are done. It is a good idea to ensure that for every new you have a delete

rerun Over a year ago

You can't create an array of any size where you get the size at runtime. You can create a pointer to a buffer of n elements that acts like an array but you will have to delete it. Thats one of the many reason using the stl containers are preferable.

Cody Gray · Accepted Answer · 2012-01-20 22:37:23Z

1

I think that should be:

std::cin >> collection[i];

edited Jan 20, 2012 at 22:37

Cody Gray♦

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answered Jan 20, 2012 at 22:29

steve8918

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Comments

Mark Ransom · Accepted Answer · 2012-01-20 22:28:58Z

0

I think it's a simple typo. std::cin>>wordsCollection[i] should be std::cin>>collection[i].

answered Jan 20, 2012 at 22:28

Mark Ransom

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Comments

thpatel · Accepted Answer · 2012-01-20 22:30:36Z

0

Try the following:

#include <vector>
#include <string>
#include <iostream>

int main(int argc, char* argv[])
{
    std::vector<std::string> myStrings;
    myStrings.push_back(std::string("string1"));
    myStrings.push_back(std::string("string2"));

    std::vector<std::string>::iterator iter = myStrings.begin();
    std::vector<std::string>::iterator end = myStrings.end();
    while(iter != end)
    {
        std::cout << (*iter) << std::endl;
        ++iter;
    }
    return 0;
}

answered Jan 20, 2012 at 22:30

thpatel

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Comments

Cody Gray · Accepted Answer · 2012-01-20 22:37:48Z

0

You're getting this error because you're trying access the elements of an int (i.e. wordsCollection), not an array of int (i.e. collection). What you should be writing is

std::cin>>collection[i]

edited Jan 20, 2012 at 22:37

Cody Gray♦

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answered Jan 20, 2012 at 22:29

conectionist

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