I got this doubt while writing some code. Is 'bool' a basic datatype defined in the C++ standard or is it some sort of extension provided by the compiler ? I got this doubt because Win32 has 'BOOL' which is nothing but a typedef of long. Also what happens if I do something like this:
int i = true;
Is it "always" guaranteed that variable i will have value 1 or is it again depends on the compiler I am using ? Further for some Win32 APIs which accept BOOL as the parameter what happens if I pass bool variable?
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Yes, bool is a built-in type.
WIN32 is C code, not C++, and C does not have a bool, so they provide their own typedef BOOL.
Allthough it's now a native type, it's still defined behind the scenes as an integer (int I think) where the literal false is 0 and true is 1. But I think all logic still consider anything but 0 as true, so strictly speaking the true literal is probably a keyword for the compiler to test if something is not false.
if(someval == true){
probably translates to:
if(someval !== false){ // e.g. someval !== 0
by the compiler
C++ does lots of automatic casting for you - that is, if you have a variable of type bool and pass it to something expecting an int, it will make it into an int for you - 0 for false and 1 for true.
I don't have my standard around to see if this is guaranteed, but every compiler I've used does this (so one can assume it will always work).
However, relying on this conversion is a bad idea. Code can stop compiling if a new method is added that overloads the int signature, etc.
Yes, bool is a built-in type.
WIN32 is C code, not C++, and C does not have a bool, so they provide their own typedef BOOL.
yes, it was introduced in 1993.
for further reference: Boolean Datatype
C is meant to be a step above assembly language. The C if-statement is really just syntactical sugar for "branch-if-zero", so the idea of booleans as an independent datatype was a foreign concept at the time. (1)
Even now, C/C++ booleans are usually little more than an alias for a single byte data type. As such, it's really more of a purposing label than an independent datatype.
(1) Of course, modern compilers are a bit more advanced in their handling of if statements. This is from the standpoint of C as a new language.
Yes, bool is a built-in type.
WIN32 is C code, not C++, and C does not have a bool, so they provide their own typedef BOOL.
C is meant to be a step above assembly language. The C if-statement is really just syntactical sugar for "branch-if-zero", so the idea of booleans as an independent datatype was a foreign concept at the time. (1)
Even now, C/C++ booleans are usually little more than an alias for a single byte data type. As such, it's really more of a purposing label than an independent datatype.
(1) Of course, modern compilers are a bit more advanced in their handling of if statements. This is from the standpoint of C as a new language.
Yes, C++ supports bool and it is a data type. For reference - Bool data type
yes, it was introduced in 1993.
for further reference: Boolean Datatype
Yes, bool is a built-in type.
WIN32 is C code, not C++, and C does not have a bool, so they provide their own typedef BOOL.
C is meant to be a step above assembly language. The C if-statement is really just syntactical sugar for "branch-if-zero", so the idea of booleans as an independent datatype was a foreign concept at the time. (1)
Even now, C/C++ booleans are usually little more than an alias for a single byte data type. As such, it's really more of a purposing label than an independent datatype.
(1) Of course, modern compilers are a bit more advanced in their handling of if statements. This is from the standpoint of C as a new language.
Turbo c and c++ compiler does not support boolean (bool keyword) data type but dev c++ compiler supports boolean (bool keyword) data type.
yes, it was introduced in 1993.
for further reference: Boolean Datatype
Yes, C++ supports bool and it is a data type. For reference - Bool data type
C++ does lots of automatic casting for you - that is, if you have a variable of type bool and pass it to something expecting an int, it will make it into an int for you - 0 for false and 1 for true.
I don't have my standard around to see if this is guaranteed, but every compiler I've used does this (so one can assume it will always work).
However, relying on this conversion is a bad idea. Code can stop compiling if a new method is added that overloads the int signature, etc.
Turbo c and c++ compiler does not support boolean (bool keyword) data type but dev c++ compiler supports boolean (bool keyword) data type.
C++ does lots of automatic casting for you - that is, if you have a variable of type bool and pass it to something expecting an int, it will make it into an int for you - 0 for false and 1 for true.
I don't have my standard around to see if this is guaranteed, but every compiler I've used does this (so one can assume it will always work).
However, relying on this conversion is a bad idea. Code can stop compiling if a new method is added that overloads the int signature, etc.
Allthough it's now a native type, it's still defined behind the scenes as an integer (int I think) where the literal false is 0 and true is 1. But I think all logic still consider anything but 0 as true, so strictly speaking the true literal is probably a keyword for the compiler to test if something is not false.
if(someval == true){
probably translates to:
if(someval !== false){ // e.g. someval !== 0
by the compiler
C++ does lots of automatic casting for you - that is, if you have a variable of type bool and pass it to something expecting an int, it will make it into an int for you - 0 for false and 1 for true.
I don't have my standard around to see if this is guaranteed, but every compiler I've used does this (so one can assume it will always work).
However, relying on this conversion is a bad idea. Code can stop compiling if a new method is added that overloads the int signature, etc.
yes, it was introduced in 1993.
for further reference: Boolean Datatype
Source: Stackoverflow.com