C# for Beginners: Make Your Own MP3 Player, Free

Go to File->New Project.

Select "Windows Form Application", type a name for the project and click OK.

Your new project will be created with a blank form. You can already run it by clicking the green run button. It's not very exciting though. Change the name of the form by clicking on the form and changing the text property in the properties browser on the right-hand side.

Hover your mouse over the toolbox to make it open. It's on the left-hand side. Drag three buttons and a label onto your form.

Select each of the buttons in turn and change their name properties to "open", "play" and "stop". Also change the text properties to meaningful text, like "Open", "Play" and "Stop" respectively.

Move the buttons and the label to nice positions. Resize the form if you feel like it.

Finally, add an "OpenFileDialog" to your form in the same way. It'll appear in its own area below your form when you try to place it on the form.

OK, no-one will blame you if you can't do this without looking at the answer. You sort of either happen to know it or you don't. Even if you've been writing C# for a while, there's no reason why you should know this stuff necessarily.

Go to Project->Add Class. Type a name for the class such as "MusicPlayer" and click OK.

You need to add a DllImport attribute to your class, plus the prototype for mciSendString.

Basically, paste this over your class.

using System.Runtime.InteropServices;
using System.Text;

namespace MP3_Player
{
    class MusicPlayer
    {
        [DllImport("winmm.dll")]
        private static extern long mciSendString(string lpstrCommand, StringBuilder lpstrReturnString, int uReturnLength, int hwndCallback);
    }
}

The DllImport attribute will allow us to access functionality in winmm.dll, allowing us to play mp3s.

This is a bit of a hack really, but there's no way to do this, as far as I know, in ordinary out-of-the-box C#.

Next we'll add stubs for the open, play and stop methods.

using System.Runtime.InteropServices;
using System.Text;

namespace MP3_Player
{
    class MusicPlayer
    {
        [DllImport("winmm.dll")]
        private static extern long mciSendString(string lpstrCommand, StringBuilder lpstrReturnString, int uReturnLength, int hwndCallback);

        public void open(string file)
        {
        }

        public void play()
        {
        }

        public void stop()
        {
        }
    }
}

Now we need to make the methods actually functional. We'll use the mciSendString function to send Windows commands telling it to do stuff with our mp3 file.

Note the "MyMp3" in the command strings; this is just a handle that we've made up for our mp3 file. You can use any handle you like.

using System.Runtime.InteropServices;
using System.Text;

namespace MP3_Player
{
    class MusicPlayer
    {
        [DllImport("winmm.dll")]
        private static extern long mciSendString(string lpstrCommand, StringBuilder lpstrReturnString, int uReturnLength, int hwndCallback);

        public void open(string file)
        {
            string command = "open \"" + file + "\" type MPEGVideo alias MyMp3";
            mciSendString(command, null, 0, 0);
        }

        public void play()
        {
            string command = "play MyMp3";
            mciSendString(command, null, 0, 0);
        }

        public void stop()
        {
            string command = "stop MyMp3";
            mciSendString(command, null, 0, 0);

            command = "close MyMp3";
            mciSendString(command, null, 0, 0);
        }
    }
}

Firstly, give your form a MusicPlayer to work with.

Right click "Form1.cs" in the solution explorer on the right and select "view code".

Add a new MusicPlayer instance variable and set it equal to a new music player object.

So your form now looks like this:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace MP3_Player
{
    public partial class Form1 : Form
    {
        MusicPlayer player = new MusicPlayer();

        public Form1()
        {
            InitializeComponent();
        }
    }
}

Double-click the open button that you added to your form earlier and add a command to create an "open file" dialog in the handler that C# automatically creates.

private void open_Click(object sender, EventArgs e)
{
     openFileDialog1.ShowDialog();
}

Double-click the open file dialog control (in Design View) and add some code that tells the music player to play the opened file. Set the label's text to the filename too.

private void openFileDialog1_FileOk(object sender, CancelEventArgs e)
{
      label1.Text = openFileDialog1.FileName;
      player.open(openFileDialog1.FileName);
}

Double-click the play button and add a command to tell the music player to play the file.

private void play_Click(object sender, EventArgs e)
{
      player.play();
}

Finally, implement the stop handler in the same way (double-click the stop button).

private void stop_Click(object sender, EventArgs e)
{
      player.stop();
}

Be sure to add these bits of code in by double-clicking the controls and then filling in the bit inside the handler --- if you just type these snippets yourself, you'll be missing the code that hooks up the corresponding events to the handlers.

The completed form.cs class looks like this:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace MP3_Player
{
    public partial class Form1 : Form
    {
        MusicPlayer player = new MusicPlayer();

        public Form1()
        {
            InitializeComponent();
        }

        private void open_Click(object sender, EventArgs e)
        {
            openFileDialog1.ShowDialog();
        }

        private void openFileDialog1_FileOk(object sender, CancelEventArgs e)
        {
            label1.Text = openFileDialog1.FileName;
            player.open(openFileDialog1.FileName);
        }

        private void play_Click(object sender, EventArgs e)
        {
            player.play();
        }

        private void stop_Click(object sender, EventArgs e)
        {
            player.stop();
        }
    }
}