When using the Trace class, a mechanism for recording messages that are sent to it are necessary. This is done by the use of listeners. The purpose of a listener is to collect store, and route tracing messages.
To send output to the listeners collection :
System.Diagnostics.Trace.WriteLine("Attempting to load form.");
The following example shows how to use a listener to send an output to a file:
System.Diagnostics.Trace.Listeners.Clear();
System.Diagnostics.Trace.Listeners.Add(
new System.Diagnostics.TextWriterTraceListener(@"C:\traceOutput.txt"));
The listener can also be configured by means of an application configuration file (App.config):
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.diagnostics >
<trace autoflush="true" >
<listeners>
<clear />
<add name="textWriterListener"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="C:\traceOutput.txt">
</add>
</listeners>
</trace >
</system.diagnostics>
</configuration>
Exercise
1. Create a new C# winforms application.
2. Write a couple of trace statements in the form constructor.
public SampleForm() {
System.Diagnostics.Trace.Write("Initializing Components...");
InitializeComponent();
System.Diagnostics.Trace.WriteLine("Done");
}
3. Add an application configuration file (app.config).
4. Under configuration, add the following lines:
<system.diagnostics >
<trace autoflush="true" >
<listeners>
<clear />
<add name="textWriterListener"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="C:\traceOutput.txt">
</add>
</listeners>
</trace >
</system.diagnostics>
5. Run the application. The application will generate a C:\traceOutput.txt which contains the trace statements added in the form constructor.
