Use of “this” keyword in C++ [duplicate]
up vote
52
down vote
favorite
Possible Duplicate:
Is excessive use of this in C++ a code smell
When should you use the "this" keyword in C++?
Is there any reason to use this->
In C++, is the keyword this usually omitted? For example:
Person::Person(int age) {
_age = age;
}
As opposed to:
Person::Person(int age) {
this->_age = age;
}
c++ this
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
marked as duplicate by Kev Jul 21 '11 at 16:46
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
add a comment |
up vote
52
down vote
favorite
Possible Duplicate:
Is excessive use of this in C++ a code smell
When should you use the "this" keyword in C++?
Is there any reason to use this->
In C++, is the keyword this usually omitted? For example:
Person::Person(int age) {
_age = age;
}
As opposed to:
Person::Person(int age) {
this->_age = age;
}
c++ this
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
marked as duplicate by Kev Jul 21 '11 at 16:46
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
7
most people use it when the variable passed to the function has the same name as the instance variable...
– HRÓÐÓLFR
Jul 21 '11 at 16:44
add a comment |
up vote
52
down vote
favorite
up vote
52
down vote
favorite
Possible Duplicate:
Is excessive use of this in C++ a code smell
When should you use the "this" keyword in C++?
Is there any reason to use this->
In C++, is the keyword this usually omitted? For example:
Person::Person(int age) {
_age = age;
}
As opposed to:
Person::Person(int age) {
this->_age = age;
}
c++ this
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
Possible Duplicate:
Is excessive use of this in C++ a code smell
When should you use the "this" keyword in C++?
Is there any reason to use this->
In C++, is the keyword this usually omitted? For example:
Person::Person(int age) {
_age = age;
}
As opposed to:
Person::Person(int age) {
this->_age = age;
}
c++ this
c++ this
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
edited Aug 7 at 13:46
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
asked Jul 21 '11 at 16:41
moteutsch
2,29532135
2,29532135
marked as duplicate by Kev Jul 21 '11 at 16:46
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
marked as duplicate by Kev Jul 21 '11 at 16:46
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
7
most people use it when the variable passed to the function has the same name as the instance variable...
– HRÓÐÓLFR
Jul 21 '11 at 16:44
add a comment |
7
most people use it when the variable passed to the function has the same name as the instance variable...
– HRÓÐÓLFR
Jul 21 '11 at 16:44
7
7
most people use it when the variable passed to the function has the same name as the instance variable...
– HRÓÐÓLFR
Jul 21 '11 at 16:44
most people use it when the variable passed to the function has the same name as the instance variable...
– HRÓÐÓLFR
Jul 21 '11 at 16:44
add a comment |
6 Answers
6
active
oldest
votes
up vote
73
down vote
accepted
Yes, it is not required and is usually omitted. It might be required for accessing variables after they have been overridden in the scope though:
Person::Person() {
int age;
this->age = 1;
}
Also, this:
Person::Person(int age) {
_age = age;
}
It is pretty bad style; if you need an initializer with the same name use this notation:
Person::Person(int age) : age(age) { }
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
answered Jul 21 '11 at 16:44
orlp
66k26156244
4
I have no idea what the last syntax is called, could you give me some hint / info about what to search for to understand how does that work ?
– Stormsson
Jan 7 '16 at 22:35
13
@Stormsson Member initializer lists.
– orlp
Jan 8 '16 at 1:59
It's not just bad style, it's also less efficient than initialization. Moreover, const and reference variables must be initialized on the line they are declared.
– Alejandro Blasco
Mar 22 at 9:02
@orlp there is actually a case where you have to usethis->pointer: if you are using derived template classes. In the first compilation phase, the member variables of parent-classes need to be accessed withthis->orParentClass::to make sure the compiler knows that those are not typenames.
– Dorian
May 11 at 17:12
add a comment |
up vote
17
down vote
It's programmer preference. Personally, I love using this since it explicitly marks the object members. Of course the _ does the same thing (only when you follow the convention)
edited Mar 11 '13 at 19:21
pranavk
6092918
answered Jul 21 '11 at 16:43
Rich
5,09484777
8
The underscore only does the same thing if you follow the convention.
– R. Martinho Fernandes
Jul 21 '11 at 16:44
11
Usingthisto explicitly mark object members also only works when you follow the convention.
– Robert Martin
Nov 13 '13 at 13:12
2
Note that "the convention" @Rich has mentioned is to use an underscore prefix to indicate object members. When you do not follow the convention, the method parameter has exactly the the same name as the object member, andthisis required to avoid ambiguity. But I believe an explicitthis"works" whether or not you follow the convention.
– Tom Anderson
Jan 5 '16 at 3:11
add a comment |
up vote
6
down vote
Either way works, but many places have coding standards in place that will guide the developer one way or the other. If such a policy is not in place, just follow your heart. One thing, though, it REALLY helps the readability of the code if you do use it. especially if you are not following a naming convention on class-level variable names.
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
add a comment |
up vote
5
down vote
this points to the object in whose member function it is reffered, so it is optional.
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
add a comment |
up vote
3
down vote
For the example case above, it is usually omitted, yes. However, either way is syntactically correct.
answered Jul 21 '11 at 16:43
Chad
15k23252
add a comment |
up vote
3
down vote
Yes. unless, there is an ambiguity.
It is also used sometimes to avoid some compilers optimizing virtual function call.
answered Jul 21 '11 at 16:45
balki
10.5k1759106
12
o avoid some compilers optimizing virtual function call, How so?
– Alok Save
Jul 21 '11 at 16:47
Yes, explain please?
– Gerard
Apr 29 '14 at 16:36
add a comment |
6 Answers
6
active
oldest
votes
6 Answers
6
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
73
down vote
accepted
Yes, it is not required and is usually omitted. It might be required for accessing variables after they have been overridden in the scope though:
Person::Person() {
int age;
this->age = 1;
}
Also, this:
Person::Person(int age) {
_age = age;
}
It is pretty bad style; if you need an initializer with the same name use this notation:
Person::Person(int age) : age(age) { }
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
answered Jul 21 '11 at 16:44
orlp
66k26156244
4
I have no idea what the last syntax is called, could you give me some hint / info about what to search for to understand how does that work ?
– Stormsson
Jan 7 '16 at 22:35
13
@Stormsson Member initializer lists.
– orlp
Jan 8 '16 at 1:59
It's not just bad style, it's also less efficient than initialization. Moreover, const and reference variables must be initialized on the line they are declared.
– Alejandro Blasco
Mar 22 at 9:02
@orlp there is actually a case where you have to usethis->pointer: if you are using derived template classes. In the first compilation phase, the member variables of parent-classes need to be accessed withthis->orParentClass::to make sure the compiler knows that those are not typenames.
– Dorian
May 11 at 17:12
add a comment |
up vote
73
down vote
accepted
Yes, it is not required and is usually omitted. It might be required for accessing variables after they have been overridden in the scope though:
Person::Person() {
int age;
this->age = 1;
}
Also, this:
Person::Person(int age) {
_age = age;
}
It is pretty bad style; if you need an initializer with the same name use this notation:
Person::Person(int age) : age(age) { }
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
answered Jul 21 '11 at 16:44
orlp
66k26156244
4
I have no idea what the last syntax is called, could you give me some hint / info about what to search for to understand how does that work ?
– Stormsson
Jan 7 '16 at 22:35
13
@Stormsson Member initializer lists.
– orlp
Jan 8 '16 at 1:59
It's not just bad style, it's also less efficient than initialization. Moreover, const and reference variables must be initialized on the line they are declared.
– Alejandro Blasco
Mar 22 at 9:02
@orlp there is actually a case where you have to usethis->pointer: if you are using derived template classes. In the first compilation phase, the member variables of parent-classes need to be accessed withthis->orParentClass::to make sure the compiler knows that those are not typenames.
– Dorian
May 11 at 17:12
add a comment |
up vote
73
down vote
accepted
up vote
73
down vote
accepted
Yes, it is not required and is usually omitted. It might be required for accessing variables after they have been overridden in the scope though:
Person::Person() {
int age;
this->age = 1;
}
Also, this:
Person::Person(int age) {
_age = age;
}
It is pretty bad style; if you need an initializer with the same name use this notation:
Person::Person(int age) : age(age) { }
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
answered Jul 21 '11 at 16:44
orlp
66k26156244
Yes, it is not required and is usually omitted. It might be required for accessing variables after they have been overridden in the scope though:
Person::Person() {
int age;
this->age = 1;
}
Also, this:
Person::Person(int age) {
_age = age;
}
It is pretty bad style; if you need an initializer with the same name use this notation:
Person::Person(int age) : age(age) { }
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
answered Jul 21 '11 at 16:44
orlp
66k26156244
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
edited Nov 15 '14 at 2:31
Jonathan Leffler
553k866571009
553k866571009
answered Jul 21 '11 at 16:44
orlp
66k26156244
answered Jul 21 '11 at 16:44
orlp
66k26156244
answered Jul 21 '11 at 16:44
orlp
66k26156244
66k26156244
4
I have no idea what the last syntax is called, could you give me some hint / info about what to search for to understand how does that work ?
– Stormsson
Jan 7 '16 at 22:35
13
@Stormsson Member initializer lists.
– orlp
Jan 8 '16 at 1:59
It's not just bad style, it's also less efficient than initialization. Moreover, const and reference variables must be initialized on the line they are declared.
– Alejandro Blasco
Mar 22 at 9:02
@orlp there is actually a case where you have to usethis->pointer: if you are using derived template classes. In the first compilation phase, the member variables of parent-classes need to be accessed withthis->orParentClass::to make sure the compiler knows that those are not typenames.
– Dorian
May 11 at 17:12
add a comment |
4
I have no idea what the last syntax is called, could you give me some hint / info about what to search for to understand how does that work ?
– Stormsson
Jan 7 '16 at 22:35
13
@Stormsson Member initializer lists.
– orlp
Jan 8 '16 at 1:59
It's not just bad style, it's also less efficient than initialization. Moreover, const and reference variables must be initialized on the line they are declared.
– Alejandro Blasco
Mar 22 at 9:02
@orlp there is actually a case where you have to usethis->pointer: if you are using derived template classes. In the first compilation phase, the member variables of parent-classes need to be accessed withthis->orParentClass::to make sure the compiler knows that those are not typenames.
– Dorian
May 11 at 17:12
4
4
I have no idea what the last syntax is called, could you give me some hint / info about what to search for to understand how does that work ?
– Stormsson
Jan 7 '16 at 22:35
I have no idea what the last syntax is called, could you give me some hint / info about what to search for to understand how does that work ?
– Stormsson
Jan 7 '16 at 22:35
13
13
@Stormsson Member initializer lists.
– orlp
Jan 8 '16 at 1:59
@Stormsson Member initializer lists.
– orlp
Jan 8 '16 at 1:59
It's not just bad style, it's also less efficient than initialization. Moreover, const and reference variables must be initialized on the line they are declared.
– Alejandro Blasco
Mar 22 at 9:02
It's not just bad style, it's also less efficient than initialization. Moreover, const and reference variables must be initialized on the line they are declared.
– Alejandro Blasco
Mar 22 at 9:02
@orlp there is actually a case where you have to use
this-> pointer: if you are using derived template classes. In the first compilation phase, the member variables of parent-classes need to be accessed with this-> or ParentClass:: to make sure the compiler knows that those are not typenames.– Dorian
May 11 at 17:12
@orlp there is actually a case where you have to use
this-> pointer: if you are using derived template classes. In the first compilation phase, the member variables of parent-classes need to be accessed with this-> or ParentClass:: to make sure the compiler knows that those are not typenames.– Dorian
May 11 at 17:12
add a comment |
up vote
17
down vote
It's programmer preference. Personally, I love using this since it explicitly marks the object members. Of course the _ does the same thing (only when you follow the convention)
edited Mar 11 '13 at 19:21
pranavk
6092918
answered Jul 21 '11 at 16:43
Rich
5,09484777
8
The underscore only does the same thing if you follow the convention.
– R. Martinho Fernandes
Jul 21 '11 at 16:44
11
Usingthisto explicitly mark object members also only works when you follow the convention.
– Robert Martin
Nov 13 '13 at 13:12
2
Note that "the convention" @Rich has mentioned is to use an underscore prefix to indicate object members. When you do not follow the convention, the method parameter has exactly the the same name as the object member, andthisis required to avoid ambiguity. But I believe an explicitthis"works" whether or not you follow the convention.
– Tom Anderson
Jan 5 '16 at 3:11
add a comment |
up vote
17
down vote
It's programmer preference. Personally, I love using this since it explicitly marks the object members. Of course the _ does the same thing (only when you follow the convention)
edited Mar 11 '13 at 19:21
pranavk
6092918
answered Jul 21 '11 at 16:43
Rich
5,09484777
8
The underscore only does the same thing if you follow the convention.
– R. Martinho Fernandes
Jul 21 '11 at 16:44
11
Usingthisto explicitly mark object members also only works when you follow the convention.
– Robert Martin
Nov 13 '13 at 13:12
2
Note that "the convention" @Rich has mentioned is to use an underscore prefix to indicate object members. When you do not follow the convention, the method parameter has exactly the the same name as the object member, andthisis required to avoid ambiguity. But I believe an explicitthis"works" whether or not you follow the convention.
– Tom Anderson
Jan 5 '16 at 3:11
add a comment |
up vote
17
down vote
up vote
17
down vote
It's programmer preference. Personally, I love using this since it explicitly marks the object members. Of course the _ does the same thing (only when you follow the convention)
edited Mar 11 '13 at 19:21
pranavk
6092918
answered Jul 21 '11 at 16:43
Rich
5,09484777
It's programmer preference. Personally, I love using this since it explicitly marks the object members. Of course the _ does the same thing (only when you follow the convention)
edited Mar 11 '13 at 19:21
pranavk
6092918
answered Jul 21 '11 at 16:43
Rich
5,09484777
edited Mar 11 '13 at 19:21
pranavk
6092918
edited Mar 11 '13 at 19:21
pranavk
6092918
edited Mar 11 '13 at 19:21
pranavk
6092918
6092918
answered Jul 21 '11 at 16:43
Rich
5,09484777
answered Jul 21 '11 at 16:43
Rich
5,09484777
answered Jul 21 '11 at 16:43
Rich
5,09484777
5,09484777
8
The underscore only does the same thing if you follow the convention.
– R. Martinho Fernandes
Jul 21 '11 at 16:44
11
Usingthisto explicitly mark object members also only works when you follow the convention.
– Robert Martin
Nov 13 '13 at 13:12
2
Note that "the convention" @Rich has mentioned is to use an underscore prefix to indicate object members. When you do not follow the convention, the method parameter has exactly the the same name as the object member, andthisis required to avoid ambiguity. But I believe an explicitthis"works" whether or not you follow the convention.
– Tom Anderson
Jan 5 '16 at 3:11
add a comment |
8
The underscore only does the same thing if you follow the convention.
– R. Martinho Fernandes
Jul 21 '11 at 16:44
11
Usingthisto explicitly mark object members also only works when you follow the convention.
– Robert Martin
Nov 13 '13 at 13:12
2
Note that "the convention" @Rich has mentioned is to use an underscore prefix to indicate object members. When you do not follow the convention, the method parameter has exactly the the same name as the object member, andthisis required to avoid ambiguity. But I believe an explicitthis"works" whether or not you follow the convention.
– Tom Anderson
Jan 5 '16 at 3:11
8
8
The underscore only does the same thing if you follow the convention.
– R. Martinho Fernandes
Jul 21 '11 at 16:44
The underscore only does the same thing if you follow the convention.
– R. Martinho Fernandes
Jul 21 '11 at 16:44
11
11
Using
this to explicitly mark object members also only works when you follow the convention.– Robert Martin
Nov 13 '13 at 13:12
Using
this to explicitly mark object members also only works when you follow the convention.– Robert Martin
Nov 13 '13 at 13:12
2
2
Note that "the convention" @Rich has mentioned is to use an underscore prefix to indicate object members. When you do not follow the convention, the method parameter has exactly the the same name as the object member, and
this is required to avoid ambiguity. But I believe an explicit this "works" whether or not you follow the convention.– Tom Anderson
Jan 5 '16 at 3:11
Note that "the convention" @Rich has mentioned is to use an underscore prefix to indicate object members. When you do not follow the convention, the method parameter has exactly the the same name as the object member, and
this is required to avoid ambiguity. But I believe an explicit this "works" whether or not you follow the convention.– Tom Anderson
Jan 5 '16 at 3:11
add a comment |
up vote
6
down vote
Either way works, but many places have coding standards in place that will guide the developer one way or the other. If such a policy is not in place, just follow your heart. One thing, though, it REALLY helps the readability of the code if you do use it. especially if you are not following a naming convention on class-level variable names.
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
add a comment |
up vote
6
down vote
Either way works, but many places have coding standards in place that will guide the developer one way or the other. If such a policy is not in place, just follow your heart. One thing, though, it REALLY helps the readability of the code if you do use it. especially if you are not following a naming convention on class-level variable names.
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
add a comment |
up vote
6
down vote
up vote
6
down vote
Either way works, but many places have coding standards in place that will guide the developer one way or the other. If such a policy is not in place, just follow your heart. One thing, though, it REALLY helps the readability of the code if you do use it. especially if you are not following a naming convention on class-level variable names.
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
Either way works, but many places have coding standards in place that will guide the developer one way or the other. If such a policy is not in place, just follow your heart. One thing, though, it REALLY helps the readability of the code if you do use it. especially if you are not following a naming convention on class-level variable names.
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
answered Jul 21 '11 at 16:46
Muad'Dib
21.9k54460
21.9k54460
add a comment |
add a comment |
up vote
5
down vote
this points to the object in whose member function it is reffered, so it is optional.
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
add a comment |
up vote
5
down vote
this points to the object in whose member function it is reffered, so it is optional.
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
add a comment |
up vote
5
down vote
up vote
5
down vote
this points to the object in whose member function it is reffered, so it is optional.
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
this points to the object in whose member function it is reffered, so it is optional.
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
answered Jul 21 '11 at 16:43
Alok Save
163k35338478
163k35338478
add a comment |
add a comment |
up vote
3
down vote
For the example case above, it is usually omitted, yes. However, either way is syntactically correct.
answered Jul 21 '11 at 16:43
Chad
15k23252
add a comment |
up vote
3
down vote
For the example case above, it is usually omitted, yes. However, either way is syntactically correct.
answered Jul 21 '11 at 16:43
Chad
15k23252
add a comment |
up vote
3
down vote
up vote
3
down vote
For the example case above, it is usually omitted, yes. However, either way is syntactically correct.
answered Jul 21 '11 at 16:43
Chad
15k23252
For the example case above, it is usually omitted, yes. However, either way is syntactically correct.
answered Jul 21 '11 at 16:43
Chad
15k23252
answered Jul 21 '11 at 16:43
Chad
15k23252
answered Jul 21 '11 at 16:43
Chad
15k23252
answered Jul 21 '11 at 16:43
Chad
15k23252
15k23252
add a comment |
add a comment |
up vote
3
down vote
Yes. unless, there is an ambiguity.
It is also used sometimes to avoid some compilers optimizing virtual function call.
answered Jul 21 '11 at 16:45
balki
10.5k1759106
12
o avoid some compilers optimizing virtual function call, How so?
– Alok Save
Jul 21 '11 at 16:47
Yes, explain please?
– Gerard
Apr 29 '14 at 16:36
add a comment |
up vote
3
down vote
Yes. unless, there is an ambiguity.
It is also used sometimes to avoid some compilers optimizing virtual function call.
answered Jul 21 '11 at 16:45
balki
10.5k1759106
12
o avoid some compilers optimizing virtual function call, How so?
– Alok Save
Jul 21 '11 at 16:47
Yes, explain please?
– Gerard
Apr 29 '14 at 16:36
add a comment |
up vote
3
down vote
up vote
3
down vote
Yes. unless, there is an ambiguity.
It is also used sometimes to avoid some compilers optimizing virtual function call.
answered Jul 21 '11 at 16:45
balki
10.5k1759106
Yes. unless, there is an ambiguity.
It is also used sometimes to avoid some compilers optimizing virtual function call.
answered Jul 21 '11 at 16:45
balki
10.5k1759106
answered Jul 21 '11 at 16:45
balki
10.5k1759106
answered Jul 21 '11 at 16:45
balki
10.5k1759106
answered Jul 21 '11 at 16:45
balki
10.5k1759106
10.5k1759106
12
o avoid some compilers optimizing virtual function call, How so?
– Alok Save
Jul 21 '11 at 16:47
Yes, explain please?
– Gerard
Apr 29 '14 at 16:36
add a comment |
12
o avoid some compilers optimizing virtual function call, How so?
– Alok Save
Jul 21 '11 at 16:47
Yes, explain please?
– Gerard
Apr 29 '14 at 16:36
12
12
o avoid some compilers optimizing virtual function call, How so?– Alok Save
Jul 21 '11 at 16:47
o avoid some compilers optimizing virtual function call, How so?– Alok Save
Jul 21 '11 at 16:47
Yes, explain please?
– Gerard
Apr 29 '14 at 16:36
Yes, explain please?
– Gerard
Apr 29 '14 at 16:36
add a comment |
7
most people use it when the variable passed to the function has the same name as the instance variable...
– HRÓÐÓLFR
Jul 21 '11 at 16:44