说明：  在VB程序中，完成字符与单精度浮点数的转换，其中StringToDouble为字符串转换为单精度数，FloatToString为单精度数转换为4字节字符串。
(in VB program, complete with characters in the single precision floating point conversion, which StringToDouble to string conversion of single-precision the number of single-precision FloatToString conversion of 4-byte string.)