Questions regarding arrays and classes!!(amateur level)

hello everyone,
in C++ you have the option of not defining the number of elements you want in an array like this .

Code:

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int a[]={1,2,3,4,5,6,7};

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i want to mimic the arrays using classes, i want to mimic this very functionality for example:

Code:

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class Array
{
............
.........

.....
};

void main()
{
Array a(1,2,3,4,5,6,7);
}

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MY QUESTION IS THIS IS IT POSSIBLE TO GIVE AN UNDEFINED NUMBER OF ARGUMENTS IN A CONSTRUCTOR SO I CAN MIMIC THE ARRAY STYLE OF INITIALIZATION.


if you still dont understand the question let me be more thorough .

Code:

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int a[]={1,2,3,4,5,6};  // this is possible in c++. Remember the 
                              // number of the inputs is undefined. It
                              //  depends on the user. 

Array a(1,2,3,4,5,6,6,7);// is the same possible can i use no matter
                                // how many arguments i want?


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Code:

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{1,2,3,4,5,6}

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This is an initializer list.. not an argument list. Implementing it is a C++11 feature.

You can also have variable argument lists.. like you said.
cstdarg (stdarg.h) - C++ Reference

Quote:

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Originally Posted by manasij7479

Code:

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{1,2,3,4,5,6}

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This is an initializer list.. not an argument list. Implementing it is a C++11 feature.

You can also have variable argument lists.. like you said.
cstdarg (stdarg.h) - C++ Reference

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Sir i know its an initializer list which is used in arrays.

Code:

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int a[]={1,2,3,4,5,6};  // intializer list

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Sir what i want to know is this can i intialize a class named Array like this too as im trying to mimic the functionalities of arrays through classes.

>what i want to know is this can i intialize a class named Array like this too as im trying to mimic the functionalities of arrays through classes.
Overload the Assignment Operator to take an initializer list as the argument.

Overloading = is probably better style, but if you want to go with variadic args to the constructor:

Code:

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#include <iostream>
#include <cstdarg> // for variadic args
#include <vector>

class example {
        public:
                example (int count, ...);
};

using namespace std;

int main(int argc, const char *argv[]) {
        example (3, 1, 2, 3);
        return 0;
}

example::example (int count, ...) {
        va_list args;
        va_start(args, count);
        for (int i = 0; i < count; i++) {
                cout << va_arg(args, int) << endl;
        }
        va_end(args);
}

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that would do it ^_^
thanx alot

I would not recommend MK27's solution. Instead, I suggest you look up std::initializer_list.

Quote:

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Originally Posted by Elysia

I would not recommend MK27's solution. Instead, I suggest you look up std::initializer_list.

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btw.. is there a C++(/11) way to make functions take variable args ?
(Not passing objects of containers having variable no. of elements )

yes, you could declare a function like so:

Code:

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template<typename... Args>
void myFunc(int arg1, Args... args);

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and then call it recursively until all of the arguments were handled - ie added to the array.

An std::initializer_list is automatically created from an initializer list in C++11.
So the function would take an object, but there would be no need for you to create it.

i dont even see the similarity of the 2. MK27 example is of a single object with a variable amount of arguments.

the original code

Code:

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int a[]={1,2,3,4,5,6};  // initialization list

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is an array of objects each taking a single argument

if you wanted to create an array of a class that you could initialize a number of them using a initializer list it would be totally different.

The thing is that the size depends upon the number of arguments, one could say. The OP asked if such a thing could be done with ordinary functions (and hence constructors).

Quote:

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Originally Posted by Acorn

i dont even see the similarity of the 2. MK27 example is of a single object with a variable amount of arguments.

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Well.. the first post also contained

Quote:

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Array a(1,2,3,4,5,6,6,7);// is the same possible can i use no matter // how many arguments i want?

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Quote:

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Originally Posted by Elysia

I would not recommend MK27's solution. Instead, I suggest you look up std::initializer_list.

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I was not aware of that. It looks to have a limitation vargs doesn't have (all args must be of the same type), altho perhaps that does not matter in this case.