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Trace.WriteLineIf Method

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Definition

Namespace:
System.Diagnostics
Assembly:
System.Diagnostics.TraceSource.dll
Assembly:
System.dll
Assembly:
netstandard.dll

Writes information about the trace to the trace listeners in the Listeners collection if a condition is true.

Overloads

WriteLineIf(Boolean, Object, String)

Writes a category name and the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.
WriteLineIf(Boolean, Object)

Writes the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.
WriteLineIf(Boolean, String)

Writes a message to the trace listeners in the Listeners collection if a condition is true.
WriteLineIf(Boolean, String, String)

Writes a category name and message to the trace listeners in the Listeners collection if a condition is true.

WriteLineIf(Boolean, Object, String)

Source:
Trace.cs
Source:
Trace.cs
Source:
Trace.cs

Writes a category name and the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.

public:
 static void WriteLineIf(bool condition, System::Object ^ value, System::String ^ category);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, object? value, string? category);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, object value, string category);
[<System.Diagnostics.Conditional("TRACE")>]
static member WriteLineIf : bool * obj * string -> unit
Public Shared Sub WriteLineIf (condition As Boolean, value As Object, category As String)

Parameters

condition
Boolean

true to cause a message to be written; otherwise, false.

value
Object

An Object whose name is sent to the Listeners.

category
String

A category name used to organize the output.

Attributes
ConditionalAttribute

Examples

The following example creates a TraceSwitch named generalSwitch. This switch is set outside the code sample.

If the switch is set to the TraceLevel Error or higher, the example outputs the first error message to the Listeners. For information on adding a listener to the Listeners collection, see the TraceListenerCollection class.

Then, if the TraceLevel is set to Verbose, the example outputs the second error message on the same line as the first message. The second message is followed by a line terminator.

// Class-level declaration.
// Create a TraceSwitch.
private:
   static TraceSwitch^ generalSwitch = 
      gcnew TraceSwitch( "General", "Entire Application" );

public:
   static void MyErrorMethod( Object^ myObject, String^ category )
   {
      #if defined(TRACE)
      // Write the message if the TraceSwitch level is set
      // to Error or higher.
      Trace::WriteIf( generalSwitch->TraceError, 
         "Invalid object for category. " );
      
      // Write a second message if the TraceSwitch level is set
      // to Verbose.
      Trace::WriteLineIf( generalSwitch->TraceVerbose, 
         myObject, category );
      #endif
   }

// Class-level declaration.
 // Create a TraceSwitch.
 static TraceSwitch generalSwitch = new TraceSwitch("General", "Entire Application");

 static public void MyErrorMethod(Object myObject, string category) {
    // Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "Invalid object for category. ");

    // Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, myObject, category);
 }

' Class-level declaration.
' Create a TraceSwitch.
Private Shared generalSwitch As New TraceSwitch("General", "Entire Application")

Public Shared Sub MyErrorMethod(myObject As Object, category As String)
    ' Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "Invalid object for category. ")
    
    ' Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, myObject, category)
End Sub

Remarks

By default, the output is written to an instance of DefaultTraceListener.

The category parameter can be used to group output messages.

This method calls the WriteLine method of the trace listener.

Notes to Inheritors

You can minimize the performance penalty of instrumenting your application by using If...Then statements instead of using WriteLineIf(Boolean, String) statements. The following two code examples send the same debugging message. However, the first example is much faster when tracing is off, because if mySwitch.TraceError evaluates to false you do not call WriteLine(String). The second example always calls WriteLineIf(Boolean, String), even when mySwitch.TraceError is false and no tracing output is produced. This can result in unnecessary execution of arbitrarily complex code.

First example

if(mySwitch.TraceError)   
    Trace.WriteLine("aNumber = " + aNumber + " out of range");

Second example

Trace.WriteLineIf(mySwitch.TraceError, "aNumber = " + aNumber + " out of range");

See also

Applies to

WriteLineIf(Boolean, Object)

Source:
Trace.cs
Source:
Trace.cs
Source:
Trace.cs

Writes the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.

public:
 static void WriteLineIf(bool condition, System::Object ^ value);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, object? value);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, object value);
[<System.Diagnostics.Conditional("TRACE")>]
static member WriteLineIf : bool * obj -> unit
Public Shared Sub WriteLineIf (condition As Boolean, value As Object)

Parameters

condition
Boolean

true to cause a message to be written; otherwise, false.

value
Object

An Object whose name is sent to the Listeners.

Attributes
ConditionalAttribute

Examples

The following example creates a TraceSwitch named generalSwitch. This switch is set outside the code sample.

If the switch is set to the TraceLevel Error or higher, the example outputs the first error message to the Listeners. For information on adding a listener to the Listeners collection, see the TraceListenerCollection class.

Then, if the TraceLevel is set to Verbose, the example outputs the name of the object on the same line as the first message. The second message is followed by a line terminator.

// Class-level declaration.
// Create a TraceSwitch.
private:
   static TraceSwitch^ generalSwitch = 
      gcnew TraceSwitch( "General", "Entire Application" );

public:
   static void MyErrorMethod( Object^ myObject )
   {
      #if defined(TRACE)
      // Write the message if the TraceSwitch level 
      // is set to Error or higher.
      Trace::WriteIf( generalSwitch->TraceError, "Invalid object. " );
      
      // Write a second message if the TraceSwitch level is set
      // to Verbose.
      Trace::WriteLineIf( generalSwitch->TraceVerbose, myObject );
      #endif
   }

// Class-level declaration.
 // Create a TraceSwitch.
 static TraceSwitch generalSwitch = new TraceSwitch("General", "Entire Application");

 static public void MyErrorMethod(Object myObject) {
    // Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "Invalid object. ");

    // Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, myObject);
 }

' Class-level declaration.
' Create a TraceSwitch.
Private Shared generalSwitch As New TraceSwitch("General", "Entire Application")


Public Shared Sub MyErrorMethod(myObject As Object)
    ' Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "Invalid object. ")
    
    ' Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, myObject)
End Sub

Remarks

By default, the output is written to an instance of DefaultTraceListener.

This method calls the WriteLine method of the trace listener.

Notes to Inheritors

You can minimize the performance penalty of instrumenting your application by using If...Then statements instead of using WriteLineIf(Boolean, String) statements. The following two code examples send the same debugging message. However, the first example is much faster when tracing is off, because if mySwitch.TraceError evaluates to false you do not call WriteLine(String). The second example always calls WriteLineIf(Boolean, String), even when mySwitch.TraceError is false and no tracing output is produced. This can result in unnecessary execution of arbitrarily complex code.

First example

if(mySwitch.TraceError)   
    Trace.WriteLine("aNumber = " + aNumber + " out of range");

Second example

Trace.WriteLineIf(mySwitch.TraceError, "aNumber = " + aNumber + " out of range");

See also

Applies to

WriteLineIf(Boolean, String)

Source:
Trace.cs
Source:
Trace.cs
Source:
Trace.cs

Writes a message to the trace listeners in the Listeners collection if a condition is true.

public:
 static void WriteLineIf(bool condition, System::String ^ message);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, string? message);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, string message);
[<System.Diagnostics.Conditional("TRACE")>]
static member WriteLineIf : bool * string -> unit
Public Shared Sub WriteLineIf (condition As Boolean, message As String)

Parameters

condition
Boolean

true to cause a message to be written; otherwise, false.

message
String

A message to write.

Attributes
ConditionalAttribute

Examples

The following example creates a TraceSwitch named generalSwitch. This switch is set outside the code sample.

If the switch is set to the TraceLevel Error or higher, the example outputs the first error message to the Listeners. For information on adding a listener to the Listeners collection, see the TraceListenerCollection class.

Then, if the TraceLevel is set to Verbose, the example outputs the second error message on the same line as the first message. The second message is followed by a line terminator.

// Class-level declaration.
// Create a TraceSwitch.
private:
   static TraceSwitch^ generalSwitch = 
      gcnew TraceSwitch( "General", "Entire Application" );

public:
   static void MyErrorMethod()
   {
      #if defined(TRACE)
      // Write the message if the TraceSwitch level is set to
      // Error or higher.
      Trace::WriteIf( generalSwitch->TraceError, "My error message. " );
      
      // Write a second message if the TraceSwitch level is set
      // to Verbose.
      Trace::WriteLineIf( generalSwitch->TraceVerbose, 
         "My second error message." );
      #endif
   }

// Class-level declaration.
 // Create a TraceSwitch.
 static TraceSwitch generalSwitch = new TraceSwitch("General", "Entire Application");

 static public void MyErrorMethod() {
    // Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "My error message. ");

    // Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, "My second error message.");
 }

' Class-level declaration.
' Create a TraceSwitch.
Private Shared generalSwitch As New TraceSwitch("General", "Entire Application")

Public Shared Sub MyErrorMethod()
    ' Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "My error message. ")
    
    ' Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, "My second error message.")
End Sub

Remarks

By default, the output is written to an instance of DefaultTraceListener.

This method calls the WriteLine method of the trace listener.

Notes to Inheritors

You can minimize the performance penalty of instrumenting your application by using If...Then statements instead of using WriteLineIf(Boolean, String) statements. The following two code examples send the same debugging message. However, the first example is much faster when tracing is off, because if mySwitch.TraceError evaluates to false you do not call WriteLine(String). The second example always calls WriteLineIf(Boolean, String), even when mySwitch.TraceError is false and no tracing output is produced. This can result in unnecessary execution of arbitrarily complex code.

First example

if(mySwitch.TraceError)   
    Trace.WriteLine("aNumber = " + aNumber + " out of range");

Second example

Trace.WriteLineIf(mySwitch.TraceError, "aNumber = " + aNumber + " out of range");

See also

Applies to

WriteLineIf(Boolean, String, String)

Source:
Trace.cs
Source:
Trace.cs
Source:
Trace.cs

Writes a category name and message to the trace listeners in the Listeners collection if a condition is true.

public:
 static void WriteLineIf(bool condition, System::String ^ message, System::String ^ category);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, string? message, string? category);
[System.Diagnostics.Conditional("TRACE")]
public static void WriteLineIf (bool condition, string message, string category);
[<System.Diagnostics.Conditional("TRACE")>]
static member WriteLineIf : bool * string * string -> unit
Public Shared Sub WriteLineIf (condition As Boolean, message As String, category As String)

Parameters

condition
Boolean

true to cause a message to be written; otherwise, false.

message
String

A message to write.

category
String

A category name used to organize the output.

Attributes
ConditionalAttribute

Examples

The following example creates a TraceSwitch named generalSwitch. This switch is set outside the code sample.

If the switch is set to the TraceLevel Error or higher, the example outputs the first error message to the Listeners. For information on adding a listener to the Listeners collection, see the TraceListenerCollection class.

Then, if the TraceLevel is set to Verbose, the example outputs the second error message and the category on the same line as the first message. The second message is followed by a line terminator.

// Class-level declaration.
// Create a TraceSwitch.
private:
   static TraceSwitch^ generalSwitch = 
      gcnew TraceSwitch( "General", "Entire Application" );

public:
   static void MyErrorMethod( String^ category )
   {
      #if defined(TRACE)
      // Write the message if the TraceSwitch level is set 
      // to Error or higher.
      Trace::WriteIf( generalSwitch->TraceError, "My error message. " );
      
      // Write a second message if the TraceSwitch level is set
      // to Verbose.
      Trace::WriteLineIf( generalSwitch->TraceVerbose, 
         "My second error message.", category );
      #endif
   }

// Class-level declaration.
 // Create a TraceSwitch.
 static TraceSwitch generalSwitch = new TraceSwitch("General", "Entire Application");

 static public void MyErrorMethod(string category) {
    // Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "My error message. ");

    // Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, "My second error message.", category);
 }

' Class-level declaration.
' Create a TraceSwitch.
Private Shared generalSwitch As New TraceSwitch("General", "Entire Application")

Public Shared Sub MyErrorMethod(category As String)
    ' Write the message if the TraceSwitch level is set to Error or higher.
    Trace.WriteIf(generalSwitch.TraceError, "My error message. ")
    
    ' Write a second message if the TraceSwitch level is set to Verbose.
    Trace.WriteLineIf(generalSwitch.TraceVerbose, _
        "My second error message.", category)
End Sub

Remarks

By default, the output is written to an instance of DefaultTraceListener.

The category parameter can be used to group output messages.

This method calls the WriteLine method of the trace listener.

Notes to Inheritors

You can minimize the performance penalty of instrumenting your application by using If...Then statements instead of using WriteLineIf(Boolean, String) statements. The following two code examples send the same debugging message. However, the first example is much faster when tracing is off, because if mySwitch.TraceError evaluates to false you do not call WriteLine(String). The second example always calls WriteLineIf(Boolean, String), even when mySwitch.TraceError is false and no tracing output is produced. This can result in unnecessary execution of arbitrarily complex code.

First example

if(mySwitch.TraceError)   
    Trace.WriteLine("aNumber = " + aNumber + " out of range");

Second example

Trace.WriteLineIf(mySwitch.TraceError, "aNumber = " + aNumber + " out of range");

See also

Applies to