While循环，检查上次运行
本文关键字：运行 检查 循环 While | 更新日期: 2023-09-27 17:58:31
我的While循环有问题，这个While循环需要在上次While循环发生变化时进行更新。
这是我的代码，它在一个线程中运行：
private void CheckAllPorts()
{
while (true)
{
MultipleClock = false;
OneClock = false;
NoClock = false;
portCount = 0;
//clear the string list.
MultiplePortNames.Clear();
//create an object searcher and fill it with the path and the query provided above.
ManagementObjectSearcher searcher = new ManagementObjectSearcher(scope, query);
try
{
foreach (ManagementObject queryObj in searcher.Get())
{
if (queryObj["InstanceName"].ToString().Contains("USB") || queryObj["InstanceName"].ToString().Contains("FTDIBUS"))
{
portCount = searcher.Get().Count;
if (portCount > 1)
{
MultiplePortNames.Add(queryObj["PortName"].ToString());
form1.UpdateListBox(MultiplePortNames);
MultipleClock = true;
}
else if (portCount == 1)
{
MultiplePortNames.Add(queryObj["PortName"].ToString());
form1.UpdateListBox(MultiplePortNames);
OneClock = true;
}
}
else
{
NoClock = true;
form1.UpdateListBox(MultiplePortNames);
}
}
}
catch
{
NoClock = true;
form1.UpdateListBox(MultiplePortNames);
}
Debug.WriteLine("NoClock = " + NoClock);
Debug.WriteLine("OneClock = " + OneClock);
Debug.WriteLine("MultipleClock = " + MultipleClock);
Thread.Sleep(500);
}
}
因此，如果portCount上次是1，而这次是其他值，比如：0或4，那么它需要执行以下代码：
form1.UpdateListBox(MultiplePortNames);
当portCount上次是2，这次也是2时，不应该执行代码。
有人知道解决我问题的办法吗？
除了这段代码的整体结构存在明显问题之外（你能告诉我你计划何时退出while（true）吗？）只关注你的问题我认为你应该以这种方式改变内部循环
int lastCount = 0;
while (true)
{
portCount = 0;
MultipleClock = false;
OneClock = false;
NoClock = false;
//clear the string list.
MultiplePortNames.Clear();
//create an object searcher and fill it with the path and the query provided above.
ManagementObjectSearcher searcher = new ManagementObjectSearcher(scope, query);
try
{
portCount = searcher.Get().Count;
foreach (ManagementObject queryObj in searcher.Get())
{
if (queryObj["InstanceName"].ToString().Contains("USB") || queryObj["InstanceName"].ToString().Contains("FTDIBUS"))
{
if (portCount >= 1)
MultiplePortNames.Add(queryObj["PortName"].ToString());
}
}
}
catch
{
// Don't like an empty catch, but perhaps in this case it could be justified
}
if(portCount == 1)
OneClock = true;
else if(portCount > 1)
MultipleClock = true;
else
NoClock = true;
if(lastCount != portCount)
{
lastCount = portCount;
form1.UpdateListBox(MultiplePortNames);
}
Debug.WriteLine("NoClock = " + NoClock);
Debug.WriteLine("OneClock = " + OneClock);
Debug.WriteLine("MultipleClock = " + MultipleClock);
Thread.Sleep(500);
}
我添加了一个lastCount变量来跟踪USB端口发现代码上一个循环的结果，并将内部循环更改为仅在foreach循环结束时调用listbox更新。不知道xxxClock变量是否仍在使用。
您需要添加另一个变量来保存上一次检查的值。然后，您可以将当前金额与以前的金额进行比较，并相应地进行逻辑运算。
将该值存储为try块中的最后一步。不过，不要将int newVar=0放在while块的开头，否则将不会得到所需的结果。
您还需要稍微清理一下代码。
编辑：看起来史蒂夫刚刚做到了。（额外的var+清理）
试着这样重新排列代码：
private void CheckAllPorts()
{
while (true)
{
MultipleClock = false;
OneClock = false;
NoClock = false;
portCount = 0;
//clear the string list.
MultiplePortNames.Clear();
//create an object searcher and fill it with the path and the query provided above.
ManagementObjectSearcher searcher = new ManagementObjectSearcher(scope, query);
try
{
var results = searcher.Get().Where(queryObj=>
queryObj["InstanceName"].ToString().Contains("USB") ||
queryObj["InstanceName"].ToString().Contains("FTDIBUS"));
if (portCount != results.Count())
{
portCount = results.Count();
if (portCount > 1)
{
MultipleClock = true;
}
else if (portCount == 1)
{
OneClock = true;
}
else if (portCount == 0)
{
NoClock = true;
}
foreach (ManagementObject queryObj in results)
{
MultiplePortNames.Add(queryObj["PortName"].ToString());
}
form1.UpdateListBox(MultiplePortNames);
}
}
catch
{
NoClock = true;
form1.UpdateListBox(MultiplePortNames);
}
Debug.WriteLine("NoClock = " + NoClock);
Debug.WriteLine("OneClock = " + OneClock);
Debug.WriteLine("MultipleClock = " + MultipleClock);
Thread.Sleep(500);
}
}