Read double precision numbers from binary file
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Hello,
I have to read double precision numbers from a binary file. I'm used to do that in C, which basically looks like that for a LSB first coded file :
char *cAddress = NULL;
double value = 0;
cAddress = (char*)(value);
*cAddress = ucBuffer[uiOffset];
*(cAddress + 1) = ucBuffer[uiOffset + 1];
*(cAddress + 2) = ucBuffer[uiOffset + 2];
*(cAddress + 3) = ucBuffer[uiOffset + 3];
*(cAddress + 4) = ucBuffer[uiOffset + 4];
*(cAddress + 5) = ucBuffer[uiOffset + 5];
*(cAddress + 6) = ucBuffer[uiOffset + 6];
*(cAddress + 7) = ucBuffer[uiOffset + 7];
Now, I would like to implement that in Matlab. Do you have any idea on how I should proceed ?
Thanks a lot for supporting
Franck
采纳的回答
James Tursa
2015-3-4
编辑：James Tursa
2015-3-4
Did you mean to type the following:
cAddress = (char*)(&value); // Added the & for type punning
Otherwise, the method of getting the bytes into the double isn't apparent. In any event, you should be able to simply use fopen with the proper machinefmt option, followed by fread with the '*double' option. Are doubles the only thing(s) in the file?
3 个评论
Guillaume
2015-3-4
Yes, the OP must have forgotten the & because otherwise the code most likely crashes.
I'd add that the fread implementation of matlab is a lot more robust than the C implementation presented here, as it can deal with difference of endianness between the file and the computer doing the reading (the machinefmt option that James is referring to).
James Tursa
2015-3-4
... the code most likely crashes."
I don't even think it will compile. I would be surprised if a compiler let you convert a double value directly into a pointer.
Franck D'Araujo
2015-3-5
更多回答（1 个）
doc fread
That help page should give you the information you need on precision and other aspects of binary file reading, together with examples. It should be a lot simpler than the raw C equivalent.
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