PerformanceCounter Constructor (String, String)


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Initializes a new, read-only instance of the PerformanceCounter class and associates it with the specified system or custom performance counter on the local computer. This constructor requires that the category have a single instance.

Namespace:   System.Diagnostics
Assembly:  System (in System.dll)

public PerformanceCounter(
	string categoryName,
	string counterName


Type: System.String

The name of the performance counter category (performance object) with which this performance counter is associated.

Type: System.String

The name of the performance counter.

Exception Condition

categoryName is an empty string ("").


counterName is an empty string ("").


The category specified does not exist.


The category specified is marked as multi-instance and requires the performance counter to be created with an instance name.


categoryName and counterName have been localized into different languages.


categoryName or counterName is null.


An error occurred when accessing a system API.


The platform is Windows 98 or Windows Millennium Edition (Me), which does not support performance counters.


Code that is executing without administrative privileges attempted to read a performance counter.

The parameter strings are not case-sensitive.

Use this overload to access a counter on the local computer that belongs to a category containing a single performance counter category instance. If you attempt to use this constructor to point this PerformanceCounter instance to a category that contains multiple instances, the constructor throws an exception. This overload can access any read-only or read/write counter, but does so in a read-only mode. A PerformanceCounter instance created using this overload cannot write to the counter, even if the counter itself is read/write.

This overload of the constructor sets the CategoryName and CounterName properties to the values you pass in, sets the MachineName property to the local computer, ".", and sets the InstanceName property to an empty string ("").

This constructor initializes the performance counter and associates the instance with an existing counter (either a system or a custom counter) on the local computer. The values that you pass in for the CategoryName and CounterName properties must point to an existing performance counter on the local computer.


To read performance counters in Windows Vista, Windows XP Professional x64 Edition, or Windows Server 2003, you must either be a member of the Performance Monitor Users group or have administrative privileges.

To avoid having to elevate your privileges to access performance counters in Windows Vista, add yourself to the Performance Monitor Users group.

In Windows Vista, User Account Control (UAC) determines the privileges of a user. If you are a member of the Built-in Administrators group, you are assigned two run-time access tokens: a standard user access token and an administrator access token. By default, you are in the standard user role. To execute the code that accesses performance counters, you must first elevate your privileges from standard user to administrator. You can do this when you start an application by right-clicking the application icon and indicating that you want to run as an administrator.


for reading the performance counter category if the ReadOnly property is true. Associated enumeration: PerformanceCounterPermissionAccess.Read.


for writing the performance counter category if the ReadOnly property is false. Associated enumeration: PerformanceCounterPermissionAccess.Write.

.NET Framework
Available since 1.1
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