sizeof a boolean variable ???

[cppgans]

what is the sizeof boolean variable

does it actually use only one bit

if not why not???

can anybody explain

[LacViet]

You got it. Just one bit. Basically you only need it to hold 2 values, 0 for false, true for anything else. You can use the sizeof() operator anytime to find the size of your data variable.

[cppgans]

sizeof(bool) returns 1

sizeof(char) returns 1 as well

perhaps u shud look into it LacViet

[Bazzy]

The minimum size for a variable is 1 byte, 1 bit booleans could be created in a bit filed
sizeof() returns the size in bytes

[jeffbmartinez]

The reason why the minimum size of a variable is 1 byte it has to do with the way computers access memory. There is no way of reserving just a single bit of memory for a variable. You might say memory is accessed with a "resolution" of eight bits (or one byte).

I believe even the one bit boolean created using a bit field as mentioned by Bazzy would require a complete byte to store.

[helios]

A bit field is an std::vector<bool>. It is a specialization of vector designed to optimize memory utilization. Every element in a bit field uses exactly 1 bit. The capacity of a bit field can only grow in multiples of 8, though.

[jeffbmartinez]

helios, I believe you're thinking of std::bitset, not regular old bit fields. C++ also supports actual bit fields.

Here is some msdn documentation on bit fields (http://msdn.microsoft.com/en-us/library/ewwyfdbe.aspx).

But just to emphasize that it's not a microsoft extension: http://www.research.att.com/~bs/glossary.html#Gbitfield

The "TC++PL C.8.1" refers you to "The C++ Programming Language" book by Stroustrup.

[helios]

http://www.cplusplus.com/reference/stl/vector/
See the bottom of the page.