I use stupid thread titles.

[siavoshkc]

long double *v[1000];
const int ind =9000000;
main()
{
	for(int s=1;s<10000;s++)
	{
	
		v[s]=new long double[ind/s];
		if(v[s]) 
		{
			cout<<  v[s]  <<endl;
			for(int i=0;i<ind/s;i++) *(v[s]+i)=(long double)i;
			cout<<*(v[s]+s)<<endl;
			
		}
	}
	
	
	return 0;
}

Why this code generates error?

[ZuK]

You are trying to allocate 9999 times 4.5 million doubles, propably 8 bytes each.
Do you have that much memory in your box ?
Kurt
EDIT: sorry I read [ind/s]; as ind / 2. But it's still a lot.

[hk_mp5kpdw]

long double *v[1000];


for(int s=1;s<10000;s++)
{
    v[s]=new long double[ind/s];

Why this code generates error?

A big problem I would say is that once s is equal to or bigger than 1000 you are accessing unsafe memory areas. Did you mean for that to be 1000 and not 10000?

[SlyMaelstrom]

What is it?

Blood... Jill look around see if you can find any other clues. I'll be examining this. Hope this is not Chris' blood.

Oh and other than memory issues, there is no reason for that to generate an error. Unless of course you're talking about an error similar to "'cout' undeclared (first used yada-yada)"

[siavoshkc]

I get a strange error when I run the program: An error window with two button but no text on it. I know for big memory allocations we need Win32 functions but my program should not generate error.

[Salem]

Just do the math on how much memory you allocate!

#include <iostream>
using namespace std;
const int ind =9000000;
int main()
{
  unsigned long sum = 0;
  for(int s=1;s<10000;s++)
  {
    sum += ind/s;
  }
  cout << sum << " doubles would be allocated\n";
  cout << "Taking a total of " << sum*sizeof(double) << " bytes" << endl;

  return 0;
}

$ ./a.exe
88082647 doubles would be allocated
Taking a total of 704661176 bytes

Just 0.75GB, no biggie

[siavoshkc]

It doesn't matter how much memory it will take. Because if there is not enough memory, new simply should return a null pointer. And if the memory is big enough, again there should be no problem.
As I know if you use new for even 2GB, then Windows should use it's swap(page) file to give the program enough memory.

[John_]

Check this from the FAQ it tells you about trying to allocate more memory than you have.
http://faq.cprogramming.com/cgi-bin/...&id=1043284351

[siavoshkc]

Let me ask a question:
Please tell me what error this program generates on your PCs if any?
I think there is a problem with my system.

[John_]

This generates no visible errors for me.
Here is the output.


88082647 doubles would be allocated
Taking a total of 704661176 bytes

-EDIT-

I just realised that is the second piece of code I tested.

Here is a little bit of the first piece of code.

00490040
1
04940040
2
06BA0040
3
08290040
4
093C0040
5
0A180040
6
0AD00040
7
0B6D0040
8
0BF70040
9
0C720040
10
0CE00040
11
0D440040
12
0DA00040
13
0DF50040
14
0E440040
15
0E8E0040
16
0ED30040
17
0F140040
18
0F520040
19
0F8C0040
20
0FC30040
21
0FF80040
22
102A0040
23
105A0040
24
10880040
25
10B40040
26
10DF0040
27
11080040
28
11300040
29
11560040
30
117B0040
31
119F0040
32
11C20040
33
11E40040
34
12050040
35
12250040
36
12440040
37
12620040

That is just a little of the output.

It just keeps going allocating memory.

I didn't let it run long enough to see if it will make my system crash/freeze. But I have 512MB ram, you can figure out how much space the program tries to allocate by looking at it, then figure out if your system has enough.

[Salem]

> Please tell me what error this program generates on your PCs if any?
I don't need to run anything to tell you that

for(int s=1;s<10000;s++)
Won't fit into
long double *v[1000];

[Blackroot]

Think of it this way:

You're saying:

10000-1000=0.

But it doesnt. You are moving 9000 places past the amount of memory you alocated. And you should never alocate so much memory, especialy if you dont need it.

Mmm, Imagine this:

I'm a surgeon, I have a line where I'm suposed to end the cut, but the nurse drew a line 9x longer than what you were suposed to cut. Sence you dont know where the end is suposed to be, you cut through the whole line. Now, you end up cutting an organ and killing the patient.

The same idea applies to your program, its trying to cut somewhere that isint where its suposed to cut. Its cutting into large chunks of memory that you shouldent acess. So, you end up killing the program.

Hope that makes sence.

[siavoshkc]

long double *v[10000];
const int ind =10000000;
main()
{	
	int nfaloc=0;
	int sum=0;
	
	for(int s=1;s<10000;s++)
	{
	
		v[s]=new (nothrow) long double[ind/s];
		if(v[s]) 
		{
			
			for(int i=0;i<ind/s;i++) *(v[s]+i)=(long double)i;
			
			sum+=(ind/s);
			int fortest=0;
			cout<<  ((ind/s)*8)/(1024) 
				<<" KBs at "<< v[s] 
				<<"  Test: "; 
			for(i=0;i<ind/s;i++) {
				if(*(v[s]+i)!=(long double)i) {fortest=1;break;}
				
			}
			if(fortest==1) cout<<"Failed. ";
			else cout<<"OK. ";
			cout << "Total: "<<(sum*8)/(1024*1024)<<" MBs allocated and tested."<<endl;
		}
		else
			nfaloc++;

	}
	
	cout<<nfaloc<<" Number of allocations failed!"<<endl;
	cout<< "Press a key..."  <<endl;
	getch();
	return 0;
}

Set windows not to create page file and run it.

[CornedBee]

On a proper compiler, new throws an exception when unable to allocate space. And for heaven's sake, use constants!

const int WHATEVER = 10000;
long double *v[WHATEVER];
	for(int s=1;s<WHATEVER;s++)

Well, I corrected all errors (like your incorrect for-scoping) and ran it on my Linux box. (Without disabling swap - Linux's out-of-memory handler can be unpleasant.) Allocated 746 MBs just fine, although the swapping slowed it to a crawl, and it froze my computer for several seconds after exiting, while all the swapped-out applications were brought back in.

[siavoshkc]

Wow, sorry, I wrote the code wrongly in the first post. It was 10000 not 1000. It was right in my own code. This is why I didn't understand you.:-(