Question

我是编程新手，我创建了一个简单的mp3播放器。有一个文本框 txtCount ，当在该文本框中输入4需要播放mp3 4次..

这里我的代码总是播放一次，for循环也不起作用。

如果我在文本框中输入4当mp3文件一次播放时显示为 3次playd 而 1次需要播放这也是错误的我不能找到代码的错误。请帮我解决问题

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace mp3Player
{
    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);
        }
    }
}

请参阅错误评论

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

    namespace mp3Player
    {
        public partial class Form1 : Form
        {
            int count, times = 0;
            MusicPlayer player = new MusicPlayer();

            public Form1()
            {
                InitializeComponent();
            }

            private void txtOpen_Click(object sender, EventArgs e)
            {
                openFileDialog1.ShowDialog();
                txtCount.Enabled = true;
            }

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

            private void txtPlay_Click(object sender, EventArgs e)
            {          
                if (txtCount.Text != "")
                {
                    count = Int32.Parse(txtCount.Text);
                    txtCount.Enabled = false;


    // This is does not work

                    for (times = 0; times < count; times++)
                    {
                        player.play();
                        times++;                    
                        lblCompleted.Text = times + " times Played";
                        lblPending.Text = (count - times) + " times need to play";

                    }


                }
                else {

                    txtCount.Focus();
                }

            }

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



        }

}

Answer 1

从循环内删除times++。

for (times = 0; times < count; times++)
                {
                    player.play();
                    //times++;  //remove this line  
                    //At the end of loop 
                    //lblCompleted.Text = 3
                    //lblPending.Text = 1
                    lblCompleted.Text = times + " times Played";
                    lblPending.Text = (count - times) + " times need to play";

                }

lblCompleted.Text和lblPending.Text会显示最新的更新值。

修改您可以使用background worker播放音乐，在此期间GUI将等待更新，直到音乐结束。

Answer 2

for循环从0开始，但是播放后但在更新标签之前，times变量增加1。（你不需要在for循环中增加变量times ++（除了你想要它）

我认为您应该将代码更改为：

for (times = 1; times <= count; times++)
            {
                player.play();                 
                lblCompleted.Text = times + " times Played";
                lblPending.Text = (count - times) + " times need to play";

            }

如何在C＃表单应用程序中多次播放mp3文件？

2 个答案: