说明：  ：声卡作为一个输入输出设备，除了能播放声音，还可以用作波形显示的采集端和信号发生器直接产生 方波、正弦波和三角波，因而在测量和控制上有着广泛的应用前景。介绍了用Vc++实现声卡示波器的方 法，并给出了关键行代码。
(: Sound card as an input and output devices, in addition to play a sound, but also can be used as a waveform display of the collection of direct client and have a square wave signal generator, sine wave and triangular wave, which in the measurement and control have a wide application prospect. Introduced with Vc++ to achieve the sound card oscilloscope method of critical lines of code.)