How can read binary file one by one?

2017 6 19
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更新时间：2017 6 20
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Dear ALL
I am struggling to find the solution for binary file. I want to read one by one data. Can anyone halp this point, please.
Finally I need to read 3d coordinates data.
The binary format like as follows, Thank you for advance cooperation.
Size in bytes Type Name
9 char File Type strings
4 long Version number
Variable char Last modified date
Variable char Lap time [HH:MM:SS]
Variable char Parameter
Variable char Comment
2 short Number
2 unsigned short 1～3
8 double
8 double
8 double
8 double
8 double
8 double
4 float
4 float
2 char strings
4 float
4 float
4 float
4 float
4 float
4 float
4 float
Variable char
2 unsigned short
8 double Origin（Xdata）
8 double Origin（Ydata）
8 double Origin（Zdata）
Data 16 double (double×2)
20 float Dummy data array (float×5)
20 long Dummy data array (long×5)
Variable char Dummy data array (char×5)
4 long Number of data
8 double Xdata
8 double Ydata
Data 8 double Zdata
… … …
… … …
… … …

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Julian Hapke
Julian Hapke 2017-6-19

2 个投票

have a look at the fread function

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Jan
Jan 2017-6-19
+1. This is the best possible answer based on the given information.
@Asaduzzaman Md: Note that "Size in bytes Type Name" is neither unique nor clear. The same for "9 char File Type strings; 4 long Version number; Variable char Last modified date". This is not enough to create reliable code for reading the file. But the fread function will solve the problem - together with a precise definition of the file format.
Asaduzzaman Md
Asaduzzaman Md 2017-6-19
Dear Jan Simon Thank you very much. I have seen the fread function. I am struggling to get the series of coordinate data means x-y-z axis data. I want to retrive this axis data.Can you see the attched file please.
Jan
Jan 2017-6-20
The table does not clarify the problem. There are some fields with a variable number of chars. Without further information it is impossible to guess, how many bytes these fields have.
Walter Roberson
Walter Roberson 2017-6-20
Are the variable-length strings NUL delimited? NUL is the character for binary 0.
Should we assume that characters are ISO 8896-1 character set?
Asaduzzaman Md
Asaduzzaman Md 2017-6-20
Dear Jan Simon Thank you very much. Actually the x-y-z axis data are variable, usal range 1000-30,000. A seris of coordinate data, before that description about the data. There is no fixed bites. Data
(8 bites) double Xdata
(8 bites) double Ydata
(8 bites) double Zdata ......................
continues the series
I want to read these continues data until the end. Thank you again for advance cooperation.
Walter Roberson
Walter Roberson 2017-6-20
At the moment we do not know how to handle the variable length strings near the beginning of the file. There are multiple ways that variable-length strings can be represented. One common method is to put a byte of binary 0 (referred to as a NUL character) after the string, in which case the string extends to just before the NUL. Another common method is to put a binary value representing the number of characters before the string; this has the advantage of being able to include NUL as part of the string, but has the disadvantage of having to know ahead of time how the count is to be represented.
Walter Roberson
Walter Roberson 2017-6-20
I notice that the documentation of the format does not define the "byte order" for multi-byte variables such as unsigned short, single, or double. See https://en.wikipedia.org/wiki/Endianness for a discussion of what byte order is and why it is important.
It is common for applications designed for internet use to use "big endian", but it is common for applications designed for PC use to use "little endian". It is necessary to know the order used ahead of time.

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