Show line number in exception handling

Question

How would one display what line number caused the error and is this even possible with the way that .NET compiles its .exes?

If not is there an automated way for Exception.Message to display the sub that crapped out?

try
{
  int x = textbox1.Text;
}
catch(Exception ex)
{
     MessageBox.Show(ex.Message);
}

Answer 1

Use ex.ToString() to get the full stack trace.

You must compile with debugging symbols (.pdb files), even in release mode, to get the line numbers (this is an option in the project build properties).

Answer 2

To see the stacktrace for a given Exception, use e.StackTrace

If you need more detailed information, you can use the System.Diagnostics.StackTrace class (here is some code for you to try):

try
{
    throw new Exception();
}
catch (Exception ex)
{
    //Get a StackTrace object for the exception
    StackTrace st = new StackTrace(ex, true);

    //Get the first stack frame
    StackFrame frame = st.GetFrame(0);

    //Get the file name
    string fileName = frame.GetFileName();

    //Get the method name
    string methodName = frame.GetMethod().Name;

    //Get the line number from the stack frame
    int line = frame.GetFileLineNumber();

    //Get the column number
    int col = frame.GetFileColumnNumber();
}

This will only work if there is a pdb file available for the assembly. See the project properties - build tab - Advanced - Debug Info selection to make sure there is a pdb file.

Answer 3

If you use 'StackTrace' and include the .pdb files in the working directory, the stack trace should contain line numbers.

Answer 4

string lineNumber=e.StackTrace.Substring(e.StackTrace.Length - 7, 7);

Answer 5

this way you can Get Line number from Exception

public int GetLineNumber(Exception ex)
{

    const string lineSearch = ":line ";
    var index = ex.StackTrace.LastIndexOf(lineSearch);
    int ln=0;
    if (index != -1)
    {


        var lineNumberText = ex.StackTrace.Substring(index + lineSearch.Length);
        string lnum = System.Text.RegularExpressions.Regex.Match(lineNumberText, @"\d+").Value;
        int.TryParse(lnum,out ln);

    }
    return ln;
}

Answer 6

Line numbers will be included in the stack trace if the library which generated the exception is compiled with debug symbols. This can be a separate file (*.pdb) or embedded in the library.

For .NET Core, .NET 5 and later, to have full exception line numbers in release builds, configure the project as follows:

<PropertyGroup>    
  <DebugSymbols>true</DebugSymbols>
  <DebugType>embedded</DebugType>

    <!-- Only enable the following if the line numbers mismatch -->
    <!--<Optimize>false</Optimize>-->
    
    <!--
      Additional properties which may impact how printed line numbers match the source code line numbers are listed here:
      https://learn.microsoft.com/en-us/dotnet/core/run-time-config/compilation
    -->
</PropertyGroup>

The above configuration will include debug symbols directly with the built files, which can be published as nugets.

An alternative to the above is to restore debug packages together with the main nuget packages, which is currently not yet supported: https://github.com/NuGet/Home/issues/9667

Now get the exception line numbers:

try
{
    throw new Exception();
}
catch (Exception ex)
{
    // Get stack trace for the exception with source file information
    var st = new StackTrace(ex, true);
    // Get the top stack frame
    var frame = st.GetFrame(0);
    // Get the line number from the stack frame
    var line = frame.GetFileLineNumber();
}

Answer 7

Is it possible to simply get the top frame from the StackTrace exposed by ex?

try
{
    throw new Exception();
}
catch (Exception ex)
{
    // Get the top stack frame
    var frame = ex.StackTrace().GetFrame(0);
    // Get the line number from the stack frame
    var line = frame.GetFileLineNumber();
}