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sizeof(char) = 1
But there is nothing to say how many bits are used to define it.
On some processors this may be more than 8, so a 'char' may be larger than the common understanding of a 'byte'.
(This is not very common, but may be true for some embedded processors or DSPs.)
[ off-topic ]
AFAIK, French programmers use octet instead of byte.
However, ISO is not a French standard: :)
Quote:
C++0x Draft
The fundamental storage unit in the C++ memory model is the byte. A byte is at least large enough to contain
any member of the basic execution character set (2.3) and the eight-bit code units of the Unicode UTF-8
encoding form and is composed of a contiguous sequence of bits, the number of which is implementation-defined.
<The compiler is free to add whatever space in-between and/or after the members. Usually, the compiler will attempt to align the members in memory so that it is advantageous for the underlying OS to access that member. Therefore the total number of bytes that the struct takes up is whatever the compiler says it is, because it is the compiler that is responsible for laying out the members in memory in whichever way it sees fit.>
Okay, thanks for your guidance on this. I thought there are definite rules for calculation of size of struct. So it maybe possible that its value can vary in different programs for the same struct or even in the same program for same struct(ural) composition (i.e if we have another struct with similar fields).
Zulfi.
Yes, although it's reasonably safe to assume that two structs in the same program which have members of the same type in the same order will have the same memory layout, even if their fields have different names.
There are (nonstandard) compiler options you can use to explicitly disable padding in struct layouts. This can be useful for networking, for instance.