Array size

[Pavan]

Hi ,
Suppose if I declare like this

int n = 0;

cin >n;

int arr[n];


Suppose when we run this application, we enter value of n as 10, then
does it create an array for 10 integers or does it create only for 0?

First of all is it safe to do like that?

[Tim Love]

Re: Array size

Pavan <pavan734@gmail .comwrites:

...
>First of all is it safe to do like that?

First of all, check that it's legal ANSI C++. No doubt it will be one
day, but is it yet?

[Michael DOUBEZ]

Re: Array size

Tim Love a écrit :

Pavan <pavan734@gmail .comwrites:
>

>...
>First of all is it safe to do like that?

First of all, check that it's legal ANSI C++. No doubt it will be one
day, but is it yet?

It is valid C99 and it is true that now, most c++ compiler will accept
this code unless you specific strict compilation options (std=c89).

>>int n = 0;
>>cin >n;
>>int arr[n];

>>Suppose when we run this application, we enter value of n as 10, then
>>does it create an array for 10 integers or does it create only for 0?

It does create a array of 10 elements. It is called VLA (Variable Length
Array).

>>First of all is it safe to do like that?

I don't know; what happens if n<0 ? I guess C is silent about this case.

Do you really need it ? I guess not.
Why don't you use a plain vector ?

Michael

[Daniel T.]

Re: Array size

Pavan <pavan734@gmail .comwrote:

But what I need is I have a function like this
>
bool f(std::vector vec)
{
>
int arr[vec.size()];
......
......
.....
}

You are mistaken, you don't need to have a function like that at all.
Tell us what you are really trying to do and we can probably help you.