C++: creating multiple data structures using a for loop

Question

I have a program where I use records of the form:

// declaring a struct for each record
struct record
{
    int number;             // number of record
    vector<int> content;    // content of record    
};

Within main I then declare each record:

record batch_1;         // stores integers from 1 - 64
record batch_2;         // stores integers from 65 - 128

Where each batch stores 64 integers from a list of numbers (in this instance from a list of 128 total numbers). I would like to make this program open ended, such that the program is capable of handling any list size (with the constraint of it being a multiple of 64). Therefore, if the list size was 256 I would need four records (batch_1 - batch_4). I am not sure how I can create N-many records, but I am looking for something like this (which is clearly not the solution):

//creating the batch records
for (int i = 1; i <= (list_size / 64); i++)
{
    record batch_[i];   // each batch stores 64 integers
}

How can this be done, and will the scope of something declared within the for loop extend beyond the loop itself? I imagine an array would satisfy the scope requirement, but I am not sure how to implement it.

Why not use vector<record> batch(list_size / 64) and then init it as needed in a loop? You're already using vectors. — Gasper
– Gasper, Commented Apr 1, 2017 at 17:57
"I am not sure how I can create N-many records". You have used vector in the definition of your record. How would you define its function? — n. m. could be an AI
– n. m. could be an AI, Commented Apr 1, 2017 at 19:13

Santiago Varela · Accepted Answer · 2017-04-01 19:29:57Z

2

Like many suggested in the comments why not use a resizable vector provided by the C++ Standard Library: std::vector?

So, instead of having this:

record batch_1;         // stores integers from 1 - 64
record batch_2;         // stores integers from 65 - 128
.
.
record batch_n          // Stores integers x - y

Replace with:

std::vector<record> batches;

//And to create the the batch records
for (int i = 1; i <= (list_size / 64); i++) {
    record r;
    r.number = i;
    r.content = ....;
    batches.push_back(r); 
    // You could also declare a constructor for your record struct to facilitate instantiating it.
}

edited Apr 1, 2017 at 19:29

answered Apr 1, 2017 at 19:17

Santiago Varela

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Comments

Gaurav Kandoria · Accepted Answer · 2017-04-01 19:19:00Z

0

Why don't you try this

    // code 
    vector<record> v(list_size / 64);
    // additinal code goes here

Now,you can access your data as follow

    (v[i].content).at(j);

answered Apr 1, 2017 at 19:19

Gaurav Kandoria

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