Is it a good idea to save/load an array of struct?

I was wondering if it w开发者_开发百科as a good idea to load/save an array of a certain type of structure using fstream. Note, I am talking about loading/saving to a binary file. Should I be loading/saving independent variables such as int, float, boolean rather then a struct? The reason I ask that is because I've heard that a structure might have some type of padding which might offset the save/load.

A structure may contain padding, which will be written to the file. This is no big deal if the file is going to be read back on the same platform, using code emitted by the same compiler that did the write. However, this is difficult to guarantee, and if you cannot guarantee it, you should normally write the data in some textual format, such as XML, json or whatever.

Without serialization, your binary data will not be portable across different platform (and compilers). So if you need portability, then you need to serialize the data before storing it in file as binary.

Have a look at these:

• Boost Serialization Tutorial
• Boost Serializable Concept

It's not deprecated (it's not part of any formal spec, where should it be deprecated?), but it's extremely not portable and probably the worst way to go about serialising stuff. Use Boost.Serialization, or a similar library.

As you pointed out in your answer this will happen with writing structs this way. If you want your files to be portable across platforms, e.g. file being written on Linux i686 to opened by Solaris on Sparc then even writing individual float's won't work.

Try writing your data to something like text or XML and then zip/tar the files to make one document of them.

As Neil said, prefer textual representation of data. The XML format may be overkill. Simpler versions are Comma Separated Value (CSV) and one value per text line.