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Compile code programmatically by using C# compiler

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This article describes how to compile code from a text source by using C# compiler.

Original product version:   Visual Studio, .NET Framework
Original KB number:   304655

Summary

The Microsoft .NET Framework exposes classes that allow you to programmatically access the C# language compiler. This might be useful if you want to write your own code-compiling utilities. This article provides sample code that enables you to compile code from a text source. The application allows you to either just build the executable or build the executable and run it. Any errors that occur during the compilation process are displayed on the form.

Requirements

  • Visual Studio
  • Visual C# language compiler

Compile code by using C# compiler

The .NET Framework provides the ICodeCompiler compiler execution interface. The CSharpCodeProvider class implements this interface and provides access to instances of the C# code generator and code compiler. The following sample code creates an instance of CSharpCodeProvider and uses it to get a reference to a ICodeCompiler interface.

CSharpCodeProvider codeProvider = new CSharpCodeProvider();
ICodeCompiler icc = codeProvider.CreateCompiler();

Once you have a reference to an ICodeCompiler interface, you can use it to compile your source code. You'll pass parameters to the compiler by using the CompilerParameters class. Here is an example:

System.CodeDom.Compiler.CompilerParameters parameters = new CompilerParameters();
parameters.GenerateExecutable = true;
parameters.OutputAssembly = Output;
CompilerResults results = icc.CompileAssemblyFromSource(parameters,SourceString);

The code above uses the CompilerParameters object to tell the compiler that you want to generate an executable file (as opposed to a DLL) and that you want to output the resulting assembly to disk. The call to CompileAssemblyFromSource is where the assembly gets compiled. This method takes the parameters object and the source code, which is a string. After you compile your code, you can check to see if there were any compilation errors. You use the return value from CompileAssemblyFromSource, which is a CompilerResults object. This object contains an errors collection, which contains any errors that occurred during the compile.

if (results.Errors.Count > 0)
{
    foreach(CompilerError CompErr in results.Errors)
    {
        textBox2.Text = textBox2.Text +
            "Line number " + CompErr.Line +
            ", Error Number: " + CompErr.ErrorNumber +
            ", '" + CompErr.ErrorText + ";" +
            Environment.NewLine + Environment.NewLine;
    }
}

There are other options for compiling, such as compiling from a file. You can also batch compile, which means you can compile multiple files or sources at the same time.

Step-by-step procedure example

  1. Create a new Visual C# .NET Windows application. Form1 is created by default.

  2. Add a Button control to Form1, and then change its Text property to Build.

  3. Add another Button control to Form1, and then change its Text property to Run.

  4. Add two TextBox controls to Form1, set the Multiline property for both controls to True, and then size these controls so that you can paste multiple lines of text into each one.

  5. In the code editor, open the Form1.cs source file.

  6. In the Form1 class, paste the following button click handler.

    private void button1_Click(object sender, System.EventArgs e)
{
    CSharpCodeProvider codeProvider = new CSharpCodeProvider();
    ICodeCompiler icc = codeProvider.CreateCompiler();
    string Output = "Out.exe";
    Button ButtonObject = (Button)sender;

    textBox2.Text = "";
    System.CodeDom.Compiler.CompilerParameters parameters = new CompilerParameters();
    //Make sure we generate an EXE, not a DLL
    parameters.GenerateExecutable = true;
    parameters.OutputAssembly = Output;
    CompilerResults results = icc.CompileAssemblyFromSource(parameters, textBox1.Text);

    if (results.Errors.Count > 0)
    {
        textBox2.ForeColor = Color.Red;
        foreach (CompilerError CompErr in results.Errors)
        {
            textBox2.Text = textBox2.Text +
                        "Line number " + CompErr.Line +
                        ", Error Number: " + CompErr.ErrorNumber +
                        ", '" + CompErr.ErrorText + ";" +
                        Environment.NewLine + Environment.NewLine;
        }
    }
    else
    {
        //Successful Compile
        textBox2.ForeColor = Color.Blue;
        textBox2.Text = "Success!";
        //If we clicked run then launch our EXE
        if (ButtonObject.Text == "Run") Process.Start(Output);
    }
}

    At the beginning of the file, add these using statements:

    using System.CodeDom.Compiler;
using System.Diagnostics;
using Microsoft.CSharp;

  7. In Form1.cs, locate the Form1 constructor.

  8. After the call to InitializeComponent in the Form1 constructor, add the following code to wire the button click handler to both buttons that you added to Form1.

    public Form1()
{
    InitializeComponent();
    this.button1.Click += new System.EventHandler(this.button1_Click);
    this.button2.Click += new System.EventHandler(this.button1_Click);
}

  9. Run the project. After Form1 loads, click the Build button.

    Note

    You get a compiler error.

  10. Next, copy the following text into the textbox, replacing any existing text:

    using System;
namespace HelloWorld
{
    /// <summary>
    /// Summary description for Class1.
    /// </summary>
    class HelloWorldClass
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            Console.ReadLine();
        }
    }
}

  11. Click Build again. The compile should be successful.

  12. Click Run, and it will compile the code and run the resulting executable file. The compile creates an executable file called Out.exe, which is saved in the same folder as the application that you're running.

    Note

    You can modify the code in the textbox to see different compiler errors. For example, delete one of the semi-colons and rebuild the code.

  13. Lastly, modify the code in the textbox to output another line of text to the console window. Click Run to see the output.

References