Can I assume bool true int 1 for any C compiler

Question

Can I assume  bool true     int 1 for any C   compiler

User · Answer

I ve found different compilers return different results on true   I ve also found that one is almost always better off comparing a bool to a bool instead of an int   Those ints tend to change value over time as your program evolves and if you assume true as 1  you can get bitten by an unrelated change elsewhere in your code

User · Answer

According to the standard  you should be safe with that assumption  The C   bool type has two values - true and false with corresponding values 1 and 0   The thing to watch about for is mixing bool expressions and variables with BOOL expression and variables  The latter is defined as FALSE   0 and TRUE    FALSE  which quite often in practice means that any value different from 0 is considered TRUE   A lot of modern compilers will actually issue a warning for any code that implicitly tries to cast from BOOL to bool if the BOOL value is different than 0 or 1

User · Answer

Yes  The casts are redundant  In your expression   true    1   Integral promotion applies and the bool value will be promoted to an int and this promotion must yield 1   Reference   4 7  conv integral    4  If the source type is bool    true is converted to one

User · Answer

Charles Bailey s answer is correct  The exact wording from the C   standard is    4 7 4    If the source type is bool  the value false is converted to zero and the value true is converted to one     Edit  I see he s added the reference as well -- I ll delete this shortly  if I don t get distracted and forget     Edit2  Then again  it is probably worth noting that while the Boolean values themselves always convert to zero or one  a number of functions  especially from the C standard library  return values that are  basically Boolean   but represented as ints that are normally only required to be zero to indicate false or non-zero to indicate true  For example  the is  functions in  lt ctype h gt  only require zero or non-zero  not necessarily zero or one   If you cast that to bool  zero will convert to false  and non-zero to true  as you d expect

[c++] Can I assume (bool)true == (int)1 for any C++ compiler?

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