C#

// Instantiate a new Engine object
Engine engine = new Engine();

// Instantiate a new FileLogger to generate build log
FileLogger logger = new FileLogger();

// Set the logfile parameter to indicate the log destination
logger.Parameters = @"logfile=" + strlogFile;

// Register the logger with the engine

engine.RegisterLogger(logger);

// Build a project file
bool success = engine.BuildProjectFile(strProjectFile);

//Unregister all loggers to close the log file
engine.UnregisterAllLoggers();

if (success)
    MessageBox.Show("Build succeeded.");
else
    MessageBox.Show(@"Build failed. View " + strLogFile + " for details");

<configuration>
    <configSections>
        <section name="msbuildToolsets" type="Microsoft.Build.BuildEngine.ToolsetConfigurationSection, Microsoft.Build.Engine, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
    </configSections>
    <startup>
        <supportedRuntime version="v2.0.50727" safemode="true"/>
        <requiredRuntime version="v2.0.50727" safemode="true"/>
    </startup>
    <runtime>
        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
            <dependentAssembly>
                <assemblyIdentity name="Microsoft.Build.Framework" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
                <bindingRedirect oldVersion="0.0.0.0-99.9.9.9" newVersion="3.5.0.0"/>
            </dependentAssembly>
        </assemblyBinding>
    </runtime>
    <!-- To define one or more new toolsets, add an 'msbuildToolsets' element in this file. -->
</configuration>

str = vDateDataGridView.SelectedRows[0].Cells[0].Value.ToString();

string regexString = @"^[0-9,]{0,14}.[0-9]{0,3}$";

private void MyForm_Paint(object sender, PaintEventArgs e)
{
           // Put your code here
}

this.refresh();

e.Graphics.DrawElipse(Pens.Red, 0, 0, this.Width, this.Height);

this.Invalidate();