Define enum as flag with an or
I'm trying to create an enum as flag. I come from C#, and I want to create an equivalent in C++. I found how to create an enum as a flag in C++, but not how to re-use a member for another member value.
I do not know how to ask my question clearly so here's what I'm trying to do (C# code):
[Flags]
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
}
What I wrote in C++:
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
inline myEnum operator|(myEnum a, myEnum b)
{
return static_cast<myEnum>(static_cast<int>(a) | static_cast<int>(b));
}
But I have an error :
redefinition of 'TypeA '
Edit:
I'm very new to C++ and I forgot the compiler. There is my environment:
- I'm working on windows 10
- with Visual studio 2017
- I compile for android with Clang 3.8 and I target KitKat 4.4
- I'm using C++ 11
Edit2:
I identified the problem. In my namespace I have a class name typeA:
In a .h :
namespace myNameSpace
{
namespace myOtherNameSpace
{
class typeA {...}
}
}
There is a conflict between both. Can I modify my enum to keep myEnum.TypeA or should I rename this member ?
c++ enums
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
|
show 13 more comments
I'm trying to create an enum as flag. I come from C#, and I want to create an equivalent in C++. I found how to create an enum as a flag in C++, but not how to re-use a member for another member value.
I do not know how to ask my question clearly so here's what I'm trying to do (C# code):
[Flags]
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
}
What I wrote in C++:
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
inline myEnum operator|(myEnum a, myEnum b)
{
return static_cast<myEnum>(static_cast<int>(a) | static_cast<int>(b));
}
But I have an error :
redefinition of 'TypeA '
Edit:
I'm very new to C++ and I forgot the compiler. There is my environment:
- I'm working on windows 10
- with Visual studio 2017
- I compile for android with Clang 3.8 and I target KitKat 4.4
- I'm using C++ 11
Edit2:
I identified the problem. In my namespace I have a class name typeA:
In a .h :
namespace myNameSpace
{
namespace myOtherNameSpace
{
class typeA {...}
}
}
There is a conflict between both. Can I modify my enum to keep myEnum.TypeA or should I rename this member ?
c++ enums
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
1
You don't need to implement a custormoperator|for yourenumsince it is not a ("strongly typed") scopedenum.
– Swordfish
Nov 13 '18 at 9:48
2
Yes, please provide a Minimal, Complete, and Verifiable example. Your code builds fine for me coliru.stacked-crooked.com/a/61d1123fa137fbd2
– StoryTeller
Nov 13 '18 at 9:48
3
@Swordfish - You do if you want to assign the result back tomyEnumwithout a cast.
– StoryTeller
Nov 13 '18 at 9:48
1
@Swordfish - It's not used in definition of the enumeration. The enumerators are just names of specific values from the underlying type. So whenTypeAB = TypeA | TypeBis defined|is the built-in integer or operator, whilemyEnum e = TypeA | TypeB;would in fact use the overloaded operator (or cause an error if the operator isn't present). Same tokens mean different things in different contexts. Gotta love C++, huh?
– StoryTeller
Nov 13 '18 at 9:53
1
Use aenum classif you don't want the enumerators populate the surrounding namespace.
– Swordfish
Nov 13 '18 at 10:15
|
show 13 more comments
I'm trying to create an enum as flag. I come from C#, and I want to create an equivalent in C++. I found how to create an enum as a flag in C++, but not how to re-use a member for another member value.
I do not know how to ask my question clearly so here's what I'm trying to do (C# code):
[Flags]
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
}
What I wrote in C++:
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
inline myEnum operator|(myEnum a, myEnum b)
{
return static_cast<myEnum>(static_cast<int>(a) | static_cast<int>(b));
}
But I have an error :
redefinition of 'TypeA '
Edit:
I'm very new to C++ and I forgot the compiler. There is my environment:
- I'm working on windows 10
- with Visual studio 2017
- I compile for android with Clang 3.8 and I target KitKat 4.4
- I'm using C++ 11
Edit2:
I identified the problem. In my namespace I have a class name typeA:
In a .h :
namespace myNameSpace
{
namespace myOtherNameSpace
{
class typeA {...}
}
}
There is a conflict between both. Can I modify my enum to keep myEnum.TypeA or should I rename this member ?
c++ enums
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
I'm trying to create an enum as flag. I come from C#, and I want to create an equivalent in C++. I found how to create an enum as a flag in C++, but not how to re-use a member for another member value.
I do not know how to ask my question clearly so here's what I'm trying to do (C# code):
[Flags]
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
}
What I wrote in C++:
enum myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
inline myEnum operator|(myEnum a, myEnum b)
{
return static_cast<myEnum>(static_cast<int>(a) | static_cast<int>(b));
}
But I have an error :
redefinition of 'TypeA '
Edit:
I'm very new to C++ and I forgot the compiler. There is my environment:
- I'm working on windows 10
- with Visual studio 2017
- I compile for android with Clang 3.8 and I target KitKat 4.4
- I'm using C++ 11
Edit2:
I identified the problem. In my namespace I have a class name typeA:
In a .h :
namespace myNameSpace
{
namespace myOtherNameSpace
{
class typeA {...}
}
}
There is a conflict between both. Can I modify my enum to keep myEnum.TypeA or should I rename this member ?
c++ enums
c++ enums
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
edited Nov 13 '18 at 10:36
ctrl-alt-delor
4,15532443
4,15532443
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
asked Nov 13 '18 at 9:44
A.PissicatA.Pissicat
7131834
7131834
1
You don't need to implement a custormoperator|for yourenumsince it is not a ("strongly typed") scopedenum.
– Swordfish
Nov 13 '18 at 9:48
2
Yes, please provide a Minimal, Complete, and Verifiable example. Your code builds fine for me coliru.stacked-crooked.com/a/61d1123fa137fbd2
– StoryTeller
Nov 13 '18 at 9:48
3
@Swordfish - You do if you want to assign the result back tomyEnumwithout a cast.
– StoryTeller
Nov 13 '18 at 9:48
1
@Swordfish - It's not used in definition of the enumeration. The enumerators are just names of specific values from the underlying type. So whenTypeAB = TypeA | TypeBis defined|is the built-in integer or operator, whilemyEnum e = TypeA | TypeB;would in fact use the overloaded operator (or cause an error if the operator isn't present). Same tokens mean different things in different contexts. Gotta love C++, huh?
– StoryTeller
Nov 13 '18 at 9:53
1
Use aenum classif you don't want the enumerators populate the surrounding namespace.
– Swordfish
Nov 13 '18 at 10:15
|
show 13 more comments
1
You don't need to implement a custormoperator|for yourenumsince it is not a ("strongly typed") scopedenum.
– Swordfish
Nov 13 '18 at 9:48
2
Yes, please provide a Minimal, Complete, and Verifiable example. Your code builds fine for me coliru.stacked-crooked.com/a/61d1123fa137fbd2
– StoryTeller
Nov 13 '18 at 9:48
3
@Swordfish - You do if you want to assign the result back tomyEnumwithout a cast.
– StoryTeller
Nov 13 '18 at 9:48
1
@Swordfish - It's not used in definition of the enumeration. The enumerators are just names of specific values from the underlying type. So whenTypeAB = TypeA | TypeBis defined|is the built-in integer or operator, whilemyEnum e = TypeA | TypeB;would in fact use the overloaded operator (or cause an error if the operator isn't present). Same tokens mean different things in different contexts. Gotta love C++, huh?
– StoryTeller
Nov 13 '18 at 9:53
1
Use aenum classif you don't want the enumerators populate the surrounding namespace.
– Swordfish
Nov 13 '18 at 10:15
1
1
You don't need to implement a custorm
operator| for your enum since it is not a ("strongly typed") scoped enum.– Swordfish
Nov 13 '18 at 9:48
You don't need to implement a custorm
operator| for your enum since it is not a ("strongly typed") scoped enum.– Swordfish
Nov 13 '18 at 9:48
2
2
Yes, please provide a Minimal, Complete, and Verifiable example. Your code builds fine for me coliru.stacked-crooked.com/a/61d1123fa137fbd2
– StoryTeller
Nov 13 '18 at 9:48
Yes, please provide a Minimal, Complete, and Verifiable example. Your code builds fine for me coliru.stacked-crooked.com/a/61d1123fa137fbd2
– StoryTeller
Nov 13 '18 at 9:48
3
3
@Swordfish - You do if you want to assign the result back to
myEnum without a cast.– StoryTeller
Nov 13 '18 at 9:48
@Swordfish - You do if you want to assign the result back to
myEnum without a cast.– StoryTeller
Nov 13 '18 at 9:48
1
1
@Swordfish - It's not used in definition of the enumeration. The enumerators are just names of specific values from the underlying type. So when
TypeAB = TypeA | TypeB is defined | is the built-in integer or operator, while myEnum e = TypeA | TypeB; would in fact use the overloaded operator (or cause an error if the operator isn't present). Same tokens mean different things in different contexts. Gotta love C++, huh?– StoryTeller
Nov 13 '18 at 9:53
@Swordfish - It's not used in definition of the enumeration. The enumerators are just names of specific values from the underlying type. So when
TypeAB = TypeA | TypeB is defined | is the built-in integer or operator, while myEnum e = TypeA | TypeB; would in fact use the overloaded operator (or cause an error if the operator isn't present). Same tokens mean different things in different contexts. Gotta love C++, huh?– StoryTeller
Nov 13 '18 at 9:53
1
1
Use a
enum class if you don't want the enumerators populate the surrounding namespace.– Swordfish
Nov 13 '18 at 10:15
Use a
enum class if you don't want the enumerators populate the surrounding namespace.– Swordfish
Nov 13 '18 at 10:15
|
show 13 more comments
2 Answers
2
active
oldest
votes
To close this topic, there is the answer found thanks to Swordfish :
Replace enum by enum class
enum class myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
With simple enum you can write myEnum e = TypeA, so if a class is named TypeA, there is a conflit and you have a compilation error.
With enum class you must specify the enum myEnum e = myEnum::TypeA. This can avoid some errors and allow to have a class named TypeA
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
add a comment |
There is nothing wrong with your code - so maybe a different issue.
However, instead of the casts, etc. you may just specify the underlying enum, so your enum becomes
enum myEnum : int
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
UPDATE: that code may not work on an older compiler such as clang 3.8 - since it's a 'modern' c++ feature.
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
answered Nov 13 '18 at 10:03
darunedarune
1,084516
and is utterly useless withoutoperator|()if it should be used as flags.
– Swordfish
Nov 13 '18 at 10:04
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
To close this topic, there is the answer found thanks to Swordfish :
Replace enum by enum class
enum class myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
With simple enum you can write myEnum e = TypeA, so if a class is named TypeA, there is a conflit and you have a compilation error.
With enum class you must specify the enum myEnum e = myEnum::TypeA. This can avoid some errors and allow to have a class named TypeA
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
add a comment |
To close this topic, there is the answer found thanks to Swordfish :
Replace enum by enum class
enum class myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
With simple enum you can write myEnum e = TypeA, so if a class is named TypeA, there is a conflit and you have a compilation error.
With enum class you must specify the enum myEnum e = myEnum::TypeA. This can avoid some errors and allow to have a class named TypeA
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
add a comment |
To close this topic, there is the answer found thanks to Swordfish :
Replace enum by enum class
enum class myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
With simple enum you can write myEnum e = TypeA, so if a class is named TypeA, there is a conflit and you have a compilation error.
With enum class you must specify the enum myEnum e = myEnum::TypeA. This can avoid some errors and allow to have a class named TypeA
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
To close this topic, there is the answer found thanks to Swordfish :
Replace enum by enum class
enum class myEnum
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
With simple enum you can write myEnum e = TypeA, so if a class is named TypeA, there is a conflit and you have a compilation error.
With enum class you must specify the enum myEnum e = myEnum::TypeA. This can avoid some errors and allow to have a class named TypeA
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
edited Nov 14 '18 at 9:05
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
answered Nov 14 '18 at 8:55
A.PissicatA.Pissicat
7131834
7131834
add a comment |
add a comment |
There is nothing wrong with your code - so maybe a different issue.
However, instead of the casts, etc. you may just specify the underlying enum, so your enum becomes
enum myEnum : int
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
UPDATE: that code may not work on an older compiler such as clang 3.8 - since it's a 'modern' c++ feature.
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
answered Nov 13 '18 at 10:03
darunedarune
1,084516
and is utterly useless withoutoperator|()if it should be used as flags.
– Swordfish
Nov 13 '18 at 10:04
add a comment |
There is nothing wrong with your code - so maybe a different issue.
However, instead of the casts, etc. you may just specify the underlying enum, so your enum becomes
enum myEnum : int
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
UPDATE: that code may not work on an older compiler such as clang 3.8 - since it's a 'modern' c++ feature.
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
answered Nov 13 '18 at 10:03
darunedarune
1,084516
and is utterly useless withoutoperator|()if it should be used as flags.
– Swordfish
Nov 13 '18 at 10:04
add a comment |
There is nothing wrong with your code - so maybe a different issue.
However, instead of the casts, etc. you may just specify the underlying enum, so your enum becomes
enum myEnum : int
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
UPDATE: that code may not work on an older compiler such as clang 3.8 - since it's a 'modern' c++ feature.
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
answered Nov 13 '18 at 10:03
darunedarune
1,084516
There is nothing wrong with your code - so maybe a different issue.
However, instead of the casts, etc. you may just specify the underlying enum, so your enum becomes
enum myEnum : int
{
TypeA = 0x01,
TypeB = 0x02,
TypeC = 0x04,
TypeAB = TypeA | TypeB
};
UPDATE: that code may not work on an older compiler such as clang 3.8 - since it's a 'modern' c++ feature.
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
answered Nov 13 '18 at 10:03
darunedarune
1,084516
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
edited Nov 13 '18 at 10:38
ctrl-alt-delor
4,15532443
4,15532443
answered Nov 13 '18 at 10:03
darunedarune
1,084516
answered Nov 13 '18 at 10:03
darunedarune
1,084516
answered Nov 13 '18 at 10:03
darunedarune
1,084516
1,084516
and is utterly useless withoutoperator|()if it should be used as flags.
– Swordfish
Nov 13 '18 at 10:04
add a comment |
and is utterly useless withoutoperator|()if it should be used as flags.
– Swordfish
Nov 13 '18 at 10:04
and is utterly useless without
operator|() if it should be used as flags.– Swordfish
Nov 13 '18 at 10:04
and is utterly useless without
operator|() if it should be used as flags.– Swordfish
Nov 13 '18 at 10:04
add a comment |
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1
You don't need to implement a custorm
operator|for yourenumsince it is not a ("strongly typed") scopedenum.– Swordfish
Nov 13 '18 at 9:48
2
Yes, please provide a Minimal, Complete, and Verifiable example. Your code builds fine for me coliru.stacked-crooked.com/a/61d1123fa137fbd2
– StoryTeller
Nov 13 '18 at 9:48
3
@Swordfish - You do if you want to assign the result back to
myEnumwithout a cast.– StoryTeller
Nov 13 '18 at 9:48
1
@Swordfish - It's not used in definition of the enumeration. The enumerators are just names of specific values from the underlying type. So when
TypeAB = TypeA | TypeBis defined|is the built-in integer or operator, whilemyEnum e = TypeA | TypeB;would in fact use the overloaded operator (or cause an error if the operator isn't present). Same tokens mean different things in different contexts. Gotta love C++, huh?– StoryTeller
Nov 13 '18 at 9:53
1
Use a
enum classif you don't want the enumerators populate the surrounding namespace.– Swordfish
Nov 13 '18 at 10:15