How to create dynamic struct array in C++?

Question

Im trying to learn dynamic arrays in C++. For integer, dynamic arrays are like that:

int main()
{    
    int x;
    cin >> x;

    int *dynamic = new int[x];
    //some codes
    delete [] dynamic;

    return 0;
}

How can i create dynamic struct array? I tried this code and i failed.

struct Phone{
    char name[30];
    char number[20];
}

int main(){
    int x;
    cin >> x;

    Phone *record;
    Phone *record = new Phone[x];// Code fails here

}

Im so confused in dynamic arrays. Please help me. Thanks.

Program breaks when i tried to enter record[0].name and number — Enes F.
– Enes F., Commented Sep 21, 2014 at 19:00
What makes you think having two record declarations is necessary (or allowed) just because the type changed? — Qaz
– Qaz, Commented Sep 21, 2014 at 19:00
shldn't it be Phone *record = new Phone; then *record.name = something and *record.number = something? btw number should be of type int? — lakshmen
– lakshmen, Commented Sep 21, 2014 at 19:05

nimrodm · Accepted Answer · 2014-09-21 19:03:19Z

1

There is no difference in syntax between allocating an int and allocating a struct.

Your syntax is correct. You're just defining the record pointer twice. Remove the first definition and you're all set (oh, and missing a semicolon after the struct{} declaration).

Note that modern C++ would probably prefer using an existing STL container (vector<Phone> or similar) instead of manually calling new and delete[]. I assume this is for learning, not for production code.

answered Sep 21, 2014 at 19:03

nimrodm

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2 Comments

Enes F. Over a year ago

Can you suggest me a source about that (especially structs)?

nimrodm Over a year ago

I would just refer to Stroustrup's "The C++ Programming Language", but depending on your experience you might be looking for a more beginner-friendly book.

Jan Swart · Accepted Answer · 2014-09-21 19:18:43Z

0

I would also suggest to rather use an std::vector. It's going to save you a lot of issues and memory bugs. Just do:

struct structName 
{
     ...
}

std::vector<structName> structVector;

Then to get the values onto the vector do a

 structVector.push_back(structName{});

answered Sep 21, 2014 at 19:18

Jan Swart

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