Arrays vs. Pointers

Why do arrays have to be statically allocated while pointers may be allocated dynamically?

Because pointers aren't really allocated. Pointers are assigned, just like an integer variable would be assigned to a value. Arrays do not have to be statically allocated. Try this:

Code:

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int var = 15;
char*  arry = new arry[var];

//... later
delete arry;

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This little bit of code illustrates dynamic memory allocation with the new operator and pointer assignment.

You can create a dynamic array as follows

Code:

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int size=0;
int *val;  <--pointer

cout << "enter arr size";
cin >> size;
val = new int[size];

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originally size was zero but now you have an array that has memory dynamically allocated to it :p

Sophie

Quote:

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Originally posted by PorkyChop
Because pointers aren't really allocated. Pointers are assigned, just like an integer variable would be assigned to a value. Arrays do not have to be statically allocated. Try this:

Code:

---

int var = 15;
char*  arry = new arry[var];

//... later
delete arry;

---

This little bit of code illustrates dynamic memory allocation with the new operator and pointer assignment.

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adding on to this:

you need to delete a dynamically allocated array as follows:

delete []arry;

Another addition: an array in the C sense can still only be allocated statically. The dynamic method makes use of pointers again.

But it doesn't matter if you think in computer terms. It's just memory...

Quote:

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Originally posted by mrcowflops
Why do arrays have to be statically allocated while pointers may be allocated dynamically?

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That is the specifications of the C++ programming language.
when you declare a pointer, you only reserve space to store one memory address, then if you should allcoate more space to have an array associated with this pointer.

BTW: I don't like this type of titles for threads!