说明：  使用Qt写的单位转换工程文件。可以在米、毫米、英尺、英寸、尺寸之间任意转换。在左边文本框输入数值，右边的文本框自动显示结果，同样，在右边输入，左边自动显示结果，使用非常方便。当然还有不足之处，会陆续改进。
(Use Qt to write unit conversion project file. Can any conversion between M, mm, inches, feet, size. On the left side of the text box to enter the value on the right, the text box automatically display results, also, on the right input, automatically display the results on the left, the use is very convenient. Of course there are shortcomings, will be improved.)