help: why this code give me wrong answer
hello i copy this code from one ebook the timing class measure length of algorithm
but always the start time(time span) is equal to stop time so ....duraition=start time- stop time==>0
where is the problem
[code]
using System;
using System.Collections;
using System.Diagnostics;
class class1
{
class CArray
{
private int[] arr;
private int upper;
private int numElements;
public CArray(int size)
{
arr = new int[size];
upper = size - 1;
numElements = 0;
}
public void Insert(int item)
{
arr[numElements] = item;
numElements++;
}
public void DisplayElements()
{
for (int i = 0; i <= upper; i++)
Console.Write(arr[i] + " ");
Console.Write('\n');
}
public void Clear()
{
for (int i = 0; i <= upper; i++)
arr[i] = 0;
numElements = 0;
}
public void SelectionSort()
{
int min, temp;
for (int outer = 0; outer <= upper; outer++)
{
min = outer;
for (int inner = outer + 1; inner <= upper; inner++)
if (arr[inner] < arr[min])
min = inner;
temp = arr[outer];
arr[outer] = arr[min];
arr[min] = temp;
}
}
}
public class Timing
{
TimeSpan startingTime;
TimeSpan duration;
TimeSpan test;
public Timing()
{
startingTime = new TimeSpan(0);
duration = new TimeSpan(0);
}
public void StopTime()
{
test =
Process.GetCurrentProcess().Threads[0].
UserProcessorTime;
duration =
Process.GetCurrentProcess().Threads[0].
UserProcessorTime.
Subtract(startingTime);
}
public void startTime()
{
GC.Collect();
GC.WaitForPendingFinalizers();
startingTime =
Process.GetCurrentProcess().Threads[0].
UserProcessorTime;
}
public TimeSpan Result()
{
return duration;
}
}
static void Main()
{
Timing sortTime = new Timing();
Random rnd = new Random(100);
int numItems = 64000;
CArray theArray = new CArray(numItems);
for (int i = 0; i < numItems; i++)
theArray.Insert((int)(rnd.NextDouble() * 100));
sortTime.startTime();
theArray.SelectionSort();
sortTime.StopTime();
}
}
[/code]
Guest UserPosted Feb 27, 2009, 2:26 PM
The "Threads[0]" reference works when your program is run as a standalone exe, because there's only one thread in that process. Therefore you know that Threads[0] is your program's thread.
However, when you run it from within Visual Studio, it is running inside vshost.exe which is a multithreaded application. This means that you can no longer assume that Threads[0] is the correct thread. If you remove Threads[0], then you're looking at the user CPU time for all threads in the current process.
Guest UserPosted Feb 27, 2009, 2:15 PM
public class Timing
{
TimeSpan startingTime;
TimeSpan duration;
TimeSpan test;
public Timing()
{
}
public void StopTime()
{
test = Process.GetCurrentProcess().UserProcessorTime;
duration = test.Subtract(startingTime);
}
public void startTime()
{
GC.Collect();
GC.WaitForPendingFinalizers();
startingTime = Process.GetCurrentProcess().UserProcessorTime;
}
public TimeSpan Result()
{
return duration;
}
}