[coderzone]

Why a segmentation fault?

#include <iostream>
#include <new>
using namespace std;
struct AB {
	int A;
	int B;
};


int main(void) {
	int llength;
	llength=1111111111;
	AB *L;
	L= new AB[llength];
	L[37370197].B=-37370197;
	delete [] L;
	return 0;
}

I think it should be out of memory.

[jimblumberg]

The above code compiled and ran for me with no errors. Or segmentation faults.

What compiler and operating system are you using? What is your maximum size of an int?

I am using g++ on Linux.


Jim

[coderzone]

32 Bit WinXP and MS Visual Studio 2005

[jimblumberg]

What does numeric_limits<int>::max() return?

I get 2147483647.

Note: You must #include <limits>


Jim

[xpi0t0s]

Quote:

Originally Posted by coderzone

32 Bit WinXP and MS Visual Studio 2005

That probably explains it. You're allocating 1111111111 pairs of 4-byte ints, that's 2,222,222,222 ints and of course 2,222,222,222*8 bytes (16.55GB), which is way over the maximum 3.2GB limit of 32-bit systems. If you want to write code like that, you're going to have to upgrade to 64-bit, or find some other way around it like using sparse arrays or a disk file.

If C were "nice", yes, you should get an "out of memory" error. But C isn't nice; it assumes you know what you're doing and only falls over when it really has to.

[shabbir]

Quote:

Originally Posted by xpi0t0s

If C were "nice", yes, you should get an "out of memory" error. But C isn't nice; it assumes you know what you're doing and only falls over when it really has to.

Well Said.