Call Unmanaged Code. Part 1

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Call Unmanaged Code. Part 1 - Simple DLLImport By Vyacheslav Biktagirov

Managed world is beautiful, I have all classes I want in FrameWork.. But what if I want call some unmanaged code? For instance, I have DLL written in C++, and want use it from C#. Let's look some code. Our DLL exports some function, in CDecl convention, that sums two integers: extern "C" __declspec(dllexport) __cdecl int sum(int a,int b); And, of course, we want reuse this code in C#. We must recall, that it is no "direct" way to call unmanaged code, but we must inform the compiler, what we want to call, how, and where is needed code located.   [DllImport("TestDll.dll", EntryPoint="sum", ExactSpelling=false,CallingConvention=CallingConvention.Cdecl)] static extern int sum(int a,int b); and now we can call it like normal C# function. x=5; y=7; z=sum(x,y); // x will receive 12 Here is full C# client code - tested for Beta2.

using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Runtime.InteropServices; namespace WindowsApplication6 { ///

/// Summary description for Form1. /// public class Form1 : System.Windows.Forms.Form { private System.Windows.Forms.Button button1; private System.Windows.Forms.TextBox textBox1; private System.Windows.Forms.Label label1; private System.Windows.Forms.TextBox textBox2; private System.Windows.Forms.Label label2; private System.Windows.Forms.TextBox textBox3; ///

/// Required designer variable. /// private System.ComponentModel.Container components = null; public Form1() { // // Required for Windows Form Designer support // InitializeComponent(); // // TODO: Add any constructor code after InitializeComponent call // } ///

/// Clean up any resources being used. /// protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } #region Windows Form Designer generated code ///

/// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// private void InitializeComponent() { this.button1 = new System.Windows.Forms.Button(); this.textBox1 = new System.Windows.Forms.TextBox(); this.label1 = new System.Windows.Forms.Label(); this.textBox2 = new System.Windows.Forms.TextBox(); this.label2 = new System.Windows.Forms.Label(); this.textBox3 = new System.Windows.Forms.TextBox(); this.SuspendLayout(); // // button1 // this.button1.Location = new System.Drawing.Point(64, 192); this.button1.Name = "button1"; this.button1.Size = new System.Drawing.Size(144, 64); this.button1.TabIndex = 0; this.button1.Text = "call sum"; this.button1.Click += new System.EventHandler(this.button1_Click); // // textBox1 // this.textBox1.Location = new System.Drawing.Point(40, 120); this.textBox1.Name = "textBox1"; this.textBox1.Size = new System.Drawing.Size(72, 22); this.textBox1.TabIndex = 1; this.textBox1.Text = "2"; // // label1 // this.label1.Location = new System.Drawing.Point(128, 128); this.label1.Name = "label1"; this.label1.Size = new System.Drawing.Size(16, 16); this.label1.TabIndex = 2; this.label1.Text = "+"; // // textBox2 // this.textBox2.Location = new System.Drawing.Point(152, 120); this.textBox2.Name = "textBox2"; this.textBox2.Size = new System.Drawing.Size(56, 22); this.textBox2.TabIndex = 3; this.textBox2.Text = "3"; // // label2 // this.label2.Location = new System.Drawing.Point(224, 120); this.label2.Name = "label2"; this.label2.Size = new System.Drawing.Size(24, 23); this.label2.TabIndex = 4; this.label2.Text = "="; // // textBox3 // this.textBox3.Location = new System.Drawing.Point(248, 120); this.textBox3.Name = "textBox3"; this.textBox3.Size = new System.Drawing.Size(112, 22); this.textBox3.TabIndex = 5; this.textBox3.Text = "5"; // // Form1 // this.AutoScaleBaseSize = new System.Drawing.Size(6, 15); this.ClientSize = new System.Drawing.Size(576, 322); this.Controls.AddRange(new System.Windows.Forms.Control[] {this.textBox3,this.label2,this.textBox2,this.label1,this.textBox1,this.button1}); this.Name = "Form1"; this.Text = "Form1"; this.ResumeLayout(false); } #endregion ///

/// The main entry point for the application. /// [STAThread] static void Main() { Application.Run(new Form1()); } #region My Code #region Dll Imports [DllImport("TestDll.dll", EntryPoint="sum", ExactSpelling=false,CallingConvention=CallingConvention.Cdecl)] static extern int sum(int a,int b); #endregion #region Button Click Events private void button1_Click(object sender, System.EventArgs e) { textBox3.Text=(int.Parse(textBox1.Text)+int.Parse(textBox2.Text)).ToString(); }