Ask General Programming Questions Not Worth Their Own Thread

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Ask General Programming Questions Not Worth Their Own Thread

Femtosecond: Aug 2, 2003

I have a bit of code that I'm working on, and it has a use of '&' that I've never seen before.

quote:

switch(rand()&3)

I've seen rand() % 3 used a million times before, but never the &. It's still giving me random numbers but it seems like it's doing something a bit different. What does this do?

# ¿ Mar 3, 2008 05:48

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# ¿ Apr 28, 2024 21:24

Femtosecond: Aug 2, 2003

Argh. I'm wanting to write a bit of code to keep track of statistics about my memory pool. I want to set up this UpdateMemoryStats function as a global so I can call it anywhere (or in the main loop) and I only want one set of stats, so I figure I should make the stats static. Unfortunately I keep getting a drat unresolved external symbol error. I'm obviously missing something... I've gone over this a bunch and I think I just need someone else to look at this or something.

Or if there's a better way to do this just suggest that.

code:

MemoryPool.hpp
==============
struct MemoryPoolStats
{
	int total_allocs;
};

class MemoryPool
{
	static MemoryPoolStats	mMemoryStats;
};

void	UpdateMemoryStats(); 

-------------------------------------------
MemoryPool.cpp
==============

void UpdateMemoryStats()
{
//an example of some operation on the mMemoryStats
MemoryPool::mMemoryStats.total_allocs = 0; //<-- I guess this is bad somehow

}

# ¿ Jun 20, 2008 18:51

Femtosecond: Aug 2, 2003

In a C# application I'm wanting to make a class that has a List as a member, but I keep running into the issue that if I try to add some items to the List, but I run into the issue that the list is null. I thought that maybe I had to instantiate the list in the constructer of the class, but that didn't work either. I'm missing something obviously.

code:

public class Stuff
	{
	List<Banana> m_Stufflist;
		String		m_name;

		public Spreadsheet(String name)
		{
			m_name					= name;	
		}

so if I wanted to do something like

code:

m_Stufflist.Add(banana1);

I run into an issue because m_Stufflist is null.

# ¿ Jul 15, 2008 17:15

Femtosecond: Aug 2, 2003

DLCinferno posted:

But you're not instantiating it. You need to do either
code:
List<Banana> m_Stufflist = new List<Banana>(); 
...when you declare it, or you need to do:
code:
m_Stufflist = new List<Banana>(); 
...in the constructor.

Don't forget you still need the parens when you instantiate it. With generics it's a little confusing to have both the <> and ().

Ahh I knew I needed to create the list in some way. I actually had written in

code:

List<Banana> m_Stufflist = new List<Banana>();

in the constructor and that didn't work. Changing it to:

code:

m_Stufflist = new List<Banana>();

worked since I had already declared m_Stufflist earlier.

# ¿ Jul 15, 2008 18:03

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