bool typedef and binary compatibility

BattlePanic · 05-08-2008, 06:54 AM

I was poring over some source code and came across the following:

Code:

/* Boolean type, assignment (but not necessarily binary) compatible with
 * C++ bool */
typedef enum {sox_false, sox_true} sox_bool;

I understand that this code creates a boolean (true or false) datatype but what does the author mean by his comment on the lack of binary compatibility with C++ bool.

Does this mean that the C++ built-in bool usually compiles to a size of 1 byte whereas a C bool defined using and enumerated type is essentially an int and therefore usually 2 or 4 bytes in size?

cpjust · 05-08-2008, 07:19 AM

Quote:

Originally Posted by BattlePanic

Does this mean that the C++ built-in bool usually compiles to a size of 1 byte whereas a C bool defined using and enumerated type is essentially an int and therefore usually 2 or 4 bytes in size?

I think that's what it means.

matsp · 05-08-2008, 08:04 AM

Yes, and enum's aren't necessarily binary compatible between different compilers, e.g. one compiler may decide to use short int (2 bytes), and another compiler uses a standard or long int (4 bytes).

--
Mats

05-08-2008, 06:54 AM	#1
BattlePanic Registered User Join Date: Apr 2008 Posts: 5	bool typedef and binary compatibility I was poring over some source code and came across the following: Code: /* Boolean type, assignment (but not necessarily binary) compatible with * C++ bool */ typedef enum {sox_false, sox_true} sox_bool; I understand that this code creates a boolean (true or false) datatype but what does the author mean by his comment on the lack of binary compatibility with C++ bool. Does this mean that the C++ built-in bool usually compiles to a size of 1 byte whereas a C bool defined using and enumerated type is essentially an int and therefore usually 2 or 4 bytes in size?
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05-08-2008, 08:04 AM	#3
matsp Kernel hacker Join Date: Jul 2007 Location: Farncombe, Surrey, England Posts: 15,686	Yes, and enum's aren't necessarily binary compatible between different compilers, e.g. one compiler may decide to use short int (2 bytes), and another compiler uses a standard or long int (4 bytes). -- Mats __________________ Compilers can produce warnings - make the compiler programmers happy: Use them! Please don't PM me for help - and no, I don't do help over instant messengers.
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