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PRB: Converting MBF to IEEE in Visual Basic for Windows
Article ID: 140520 - View products that this article applies to.
This article was previously published under Q140520
Data files created with older Microsoft Basic products (Quick Basic, GW-Basic, and Basica (IBM and Compaq licensed Basic)) may not be readable by Visual Basic for Windows.
Prior to the IEEE floating point standard being widely accepted, Microsoft used an internal floating point format known as Microsoft Binary Format (MBF). The IEEE standard was introduced later and became the industry standard.
Early versions of Microsoft QuickBASIC and GW-Basic supported only MBF format. In Microsoft Basic Professional Development System (PDS) and Visual Basic for MS-DOS, functions are available to convert between MBF and IEEE formats. As Microsoft moved toward complete acceptance of the IEEE standard, however, support for the MBF format was removed.
Visual Basic for Windows uses the IEEE standard. The MBF format, however, is incompatible with the IEEE standard and data saved in this manner will not be readable.
The PDS and Visual Basic for MS-DOS products contained functions that convert between MBF format and IEEE format. These functions are not available in Visual Basic for Windows. Here are two possible workarounds to this dilemma:
Details About Method Two: Using Mbf2ieee.dllNOTE: These functions all do conversions between Microsoft Binary Format (MBF) and IEEE floating point values. Some of the newer MS-DOS-based Basic products had versions of these functions that worked differently. For example, they let you look at an IEEE number as a string without converting it to MBF. The routines described here are only provided as a way of retrieving old MBF data.
These functions provide conversions between IEEE floating point values and Microsoft Binary Format (MBF) floating point values. Below is a set of declare statements which must be included in a Visual Basic program which calls these functions:
Below is a description of each of these functions along with an example.
CVS and CVD FunctionsThese functions accept a 4-byte (CVS) or 8-byte (CVD) string as an argument. They expect the bit pattern of this string to represent a single or double precision MBF value, respectively. The function returns an IEEE result.
MKS and MKD FunctionsThese functions accept an IEEE single (MKS), or double (MKD) precision value as an argument. It then converts this value into a 4-byte or 8-byte MBF value and returns it in a string.
Potential ProblemsThere are differences between the IEEE format and MBF. For this reason precision may be lost during the translations. It is also possible that a number cannot be converted between the two formats. If this is the case, a Visual Basic Overflow (Error #6) is generated. This is a trappable error, so handle the error accordingly.
How to Get Mbf2ieee.dllThe following file is available for download from the Microsoft Download Center:
Mbf2ieee.exeFor additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
119591Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. After downloading Mbf2ieee.exe, run it to obtain Mbf2ieee.dll along with the source files and a Mbf2ieee.txt file, which is a readme that contains the text of this article.
(http://support.microsoft.com/kb/119591/EN-US/ )How to Obtain Microsoft Support Files from Online Services
Source Code Included in Mbf2ieee.exeIn addition to the .dll itself, the source code is also provided, so you can make modifications and recompile if you have Microsoft C. To recompile and build a new .DLL file, you must use Microsoft C because the routines are specific to Microsoft C and rely on the way Microsoft C returns floating point Values. This source code does not compile with Borland C.
To recompile with Microsoft C, use the following command line statements to build the DLL:
Article ID: 140520 - Last Review: August 9, 2004 - Revision: 2.2