Experiment with C programming - Waste RAM with malloc() function

Asked Nov 29 '15 at 04:40

Active Aug 15 '21 at 21:54

Viewed 146 times

I just started learning C and I want to make some experiments to get used to important elements of the language, like pointers, memory management and so.

I was wondering if I can make a program that wastes 1 GB of your RAM. Like when you execute the program, you can actually see in your Task Manager how magically 1GB of RAM is being used.

The code I think could be used would be:

int * wasteOneGigOfRAM()
{
    int *p = (int *)malloc((sizeof(int) * 256) * 1024 * 1024);
    return p;
}

That function returns the pointer so that memory can be free later with another function, something like

int * waste = wasteOneGigOfRAM();
//Have fun seeing the task manager
// ...
free(waste);

The functions will be called via menu, so I can fill the RAM and then with a menu item I can free it.

But the first function won't fill one gig of RAM. How can I actually achieve it?

edited Aug 15 '21 at 21:54

trincot

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asked Nov 29 '15 at 04:40

Juan Bonnett

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You are allocating 1024 bytes only. – ForguesR Nov 29 '15 at 04:43
@ForguesR Makes sense!, let me change my code and see if it changs anything – Juan Bonnett Nov 29 '15 at 04:44
1

It should be 1024*1024*1024. – ForguesR Nov 29 '15 at 04:46
@ForguesR I changed it to: int *p = (int *)malloc((sizeof(int) * 256) * 1024 * 1024); But still not seeing it wasting RAM, what do you think? – Juan Bonnett Nov 29 '15 at 04:51
I think you're on Linux and refused to read how virtual memory works on it. – Blindy Nov 29 '15 at 04:52
@Blindy I'm on Windows – Juan Bonnett Nov 29 '15 at 04:53
Are you filling the memory with values are simply allocating? Also, should simply be: `int *p = malloc((sizeof(int) * 256) * 1024 * 1024);` (no cast to (`int*`) – David C. Rankin Nov 29 '15 at 04:55
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@IwillnotexistIdonotexist Thank youk, I will read it! The title of that question wouldn't come up on google with the terms I was trying to use! – Juan Bonnett Nov 29 '15 at 04:57
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@JuanBonnett No problems! Keep your question here though; The topic of why `malloc()` doesn't give you memory until you actually use it is one that everyone conceptualizes differently, and so your question can serve as a [signpost to the answer](http://stackoverflow.com/help/duplicates). – Iwillnotexist Idonotexist Nov 29 '15 at 05:01

Experiment with C programming - Waste RAM with malloc() function

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