public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SwapMouseButton")]
    public extern static int SwapMouseButton(int bSwap);

    private void button1_Click(object sender, EventArgs e)
    {
        SwapMouseButton(1);
    }

    private void button2_Click(object sender, EventArgs e)
    {
        SwapMouseButton(0);
    }
}

partial class Form1
{
    /// <summary>
    /// 必需的設計器變量。
    /// </summary>
    private System.ComponentModel.IContainer components = null;

    /// <summary>
    /// 清理所有正在使用的資源。
    /// </summary>
    /// <param name="disposing">如果應釋放托管資源，為 true；否則為 false。</param>
    protected override void Dispose(bool disposing)
    {
        if (disposing && (components != null))
        {
            components.Dispose();
        }
        base.Dispose(disposing);
    }

    #region Windows 窗體設計器生成的代碼

    /// <summary>
    /// 設計器支持所需的方法 - 不要
    /// 使用代碼編輯器修改此方法的內容。
    /// </summary>
    private void InitializeComponent()
    {
        this.button1 = new System.Windows.Forms.Button();
        this.button2 = new System.Windows.Forms.Button();
        this.SuspendLayout();
        // 
        // button1
        // 
        this.button1.Location = new System.Drawing.Point(34, 52);
        this.button1.Name = "button1";
        this.button1.Size = new System.Drawing.Size(75, 23);
        this.button1.TabIndex = 0;
        this.button1.Text = "左鍵";
        this.button1.UseVisualStyleBackColor = true;
        this.button1.Click += new System.EventHandler(this.button1_Click);
        // 
        // button2
        // 
        this.button2.Location = new System.Drawing.Point(136, 52);
        this.button2.Name = "button2";
        this.button2.Size = new System.Drawing.Size(75, 23);
        this.button2.TabIndex = 1;
        this.button2.Text = "右鍵";
        this.button2.UseVisualStyleBackColor = true;
        this.button2.Click += new System.EventHandler(this.button2_Click);
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(247, 100);
        this.Controls.Add(this.button2);
        this.Controls.Add(this.button1);
        this.Name = "Form1";
        this.Text = "左右鍵的切換";
        this.ResumeLayout(false);

    }

    #endregion

    private System.Windows.Forms.Button button1;
    private System.Windows.Forms.Button button2;
}