Why to use ForwardIterator when I can achieve the same using a BidirectionalIterator or RandomAccessIterator...
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What are the performance advantages of using ForwardIterator over BidirectionalIterator or RandomAccessIterator?
c++ c++11
edited Nov 10 at 16:03
Nicol Bolas
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asked Nov 10 at 15:59
Aneesh
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closed as unclear what you're asking by Nicol Bolas, Matthieu Brucher, pirho, EdChum, rsjaffe Nov 10 at 17:05
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
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up vote
-4
down vote
favorite
What are the performance advantages of using ForwardIterator over BidirectionalIterator or RandomAccessIterator?
c++ c++11
edited Nov 10 at 16:03
Nicol Bolas
278k33455626
asked Nov 10 at 15:59
Aneesh
1356
closed as unclear what you're asking by Nicol Bolas, Matthieu Brucher, pirho, EdChum, rsjaffe Nov 10 at 17:05
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
1
Your question doesn't make sense. Who is the "you" in this scenario? Are you designing a container or iterator? Are you writing an algorithm that consumes iterators? And what makes you think that "ForwardIterator" has anything to do with performance (or at least, in the way you mean it)?
– Nicol Bolas
Nov 10 at 16:02
There aren't any -- every Bidi iterator is a forward iterator, and every random-access iterator is bidi. So you can do strictly more with the stronger guarantees. Usually when something is a forward iterator, that's because that's the best it can be.
– Kerrek SB
Nov 10 at 16:02
you have the question reversed. instead you shuold ask yourself: why would i use a bidirectional iterator, when i need to iterate only in forward direction? ... and the answer is: you dont
– user463035818
Nov 10 at 16:07
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up vote
-4
down vote
favorite
up vote
-4
down vote
favorite
What are the performance advantages of using ForwardIterator over BidirectionalIterator or RandomAccessIterator?
c++ c++11
edited Nov 10 at 16:03
Nicol Bolas
278k33455626
asked Nov 10 at 15:59
Aneesh
1356
What are the performance advantages of using ForwardIterator over BidirectionalIterator or RandomAccessIterator?
c++ c++11
c++ c++11
edited Nov 10 at 16:03
Nicol Bolas
278k33455626
asked Nov 10 at 15:59
Aneesh
1356
edited Nov 10 at 16:03
Nicol Bolas
278k33455626
asked Nov 10 at 15:59
Aneesh
1356
edited Nov 10 at 16:03
Nicol Bolas
278k33455626
edited Nov 10 at 16:03
Nicol Bolas
278k33455626
edited Nov 10 at 16:03
Nicol Bolas
278k33455626
278k33455626
asked Nov 10 at 15:59
Aneesh
1356
asked Nov 10 at 15:59
Aneesh
1356
asked Nov 10 at 15:59
Aneesh
1356
1356
closed as unclear what you're asking by Nicol Bolas, Matthieu Brucher, pirho, EdChum, rsjaffe Nov 10 at 17:05
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
closed as unclear what you're asking by Nicol Bolas, Matthieu Brucher, pirho, EdChum, rsjaffe Nov 10 at 17:05
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
1
Your question doesn't make sense. Who is the "you" in this scenario? Are you designing a container or iterator? Are you writing an algorithm that consumes iterators? And what makes you think that "ForwardIterator" has anything to do with performance (or at least, in the way you mean it)?
– Nicol Bolas
Nov 10 at 16:02
There aren't any -- every Bidi iterator is a forward iterator, and every random-access iterator is bidi. So you can do strictly more with the stronger guarantees. Usually when something is a forward iterator, that's because that's the best it can be.
– Kerrek SB
Nov 10 at 16:02
you have the question reversed. instead you shuold ask yourself: why would i use a bidirectional iterator, when i need to iterate only in forward direction? ... and the answer is: you dont
– user463035818
Nov 10 at 16:07
add a comment |
1
Your question doesn't make sense. Who is the "you" in this scenario? Are you designing a container or iterator? Are you writing an algorithm that consumes iterators? And what makes you think that "ForwardIterator" has anything to do with performance (or at least, in the way you mean it)?
– Nicol Bolas
Nov 10 at 16:02
There aren't any -- every Bidi iterator is a forward iterator, and every random-access iterator is bidi. So you can do strictly more with the stronger guarantees. Usually when something is a forward iterator, that's because that's the best it can be.
– Kerrek SB
Nov 10 at 16:02
you have the question reversed. instead you shuold ask yourself: why would i use a bidirectional iterator, when i need to iterate only in forward direction? ... and the answer is: you dont
– user463035818
Nov 10 at 16:07
1
1
Your question doesn't make sense. Who is the "you" in this scenario? Are you designing a container or iterator? Are you writing an algorithm that consumes iterators? And what makes you think that "ForwardIterator" has anything to do with performance (or at least, in the way you mean it)?
– Nicol Bolas
Nov 10 at 16:02
Your question doesn't make sense. Who is the "you" in this scenario? Are you designing a container or iterator? Are you writing an algorithm that consumes iterators? And what makes you think that "ForwardIterator" has anything to do with performance (or at least, in the way you mean it)?
– Nicol Bolas
Nov 10 at 16:02
There aren't any -- every Bidi iterator is a forward iterator, and every random-access iterator is bidi. So you can do strictly more with the stronger guarantees. Usually when something is a forward iterator, that's because that's the best it can be.
– Kerrek SB
Nov 10 at 16:02
There aren't any -- every Bidi iterator is a forward iterator, and every random-access iterator is bidi. So you can do strictly more with the stronger guarantees. Usually when something is a forward iterator, that's because that's the best it can be.
– Kerrek SB
Nov 10 at 16:02
you have the question reversed. instead you shuold ask yourself: why would i use a bidirectional iterator, when i need to iterate only in forward direction? ... and the answer is: you dont
– user463035818
Nov 10 at 16:07
you have the question reversed. instead you shuold ask yourself: why would i use a bidirectional iterator, when i need to iterate only in forward direction? ... and the answer is: you dont
– user463035818
Nov 10 at 16:07
add a comment |
1 Answer
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A more restricted iterator category doesn't normally give a performance advantage, as you'd normally use the term. Instead, it gives access to data stored in structures that aren't accessible in other ways.
Looking specifically at forward iterator, it can be used (for one example) for accessing data stored in a singly linked list, where a bidirectional iterator would normally require a doubly linked list.
Using a singly linked list could lead to a performance advantage over a doubly linked list--it only requires one pointer per node instead of two. With fewer pointers per node, you can typically expect to store more nodes in the cache, which can improve performance (considerably) by requiring fewer references to main memory.
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
A more restricted iterator category doesn't normally give a performance advantage, as you'd normally use the term. Instead, it gives access to data stored in structures that aren't accessible in other ways.
Looking specifically at forward iterator, it can be used (for one example) for accessing data stored in a singly linked list, where a bidirectional iterator would normally require a doubly linked list.
Using a singly linked list could lead to a performance advantage over a doubly linked list--it only requires one pointer per node instead of two. With fewer pointers per node, you can typically expect to store more nodes in the cache, which can improve performance (considerably) by requiring fewer references to main memory.
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
add a comment |
up vote
2
down vote
A more restricted iterator category doesn't normally give a performance advantage, as you'd normally use the term. Instead, it gives access to data stored in structures that aren't accessible in other ways.
Looking specifically at forward iterator, it can be used (for one example) for accessing data stored in a singly linked list, where a bidirectional iterator would normally require a doubly linked list.
Using a singly linked list could lead to a performance advantage over a doubly linked list--it only requires one pointer per node instead of two. With fewer pointers per node, you can typically expect to store more nodes in the cache, which can improve performance (considerably) by requiring fewer references to main memory.
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
add a comment |
up vote
2
down vote
up vote
2
down vote
A more restricted iterator category doesn't normally give a performance advantage, as you'd normally use the term. Instead, it gives access to data stored in structures that aren't accessible in other ways.
Looking specifically at forward iterator, it can be used (for one example) for accessing data stored in a singly linked list, where a bidirectional iterator would normally require a doubly linked list.
Using a singly linked list could lead to a performance advantage over a doubly linked list--it only requires one pointer per node instead of two. With fewer pointers per node, you can typically expect to store more nodes in the cache, which can improve performance (considerably) by requiring fewer references to main memory.
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
A more restricted iterator category doesn't normally give a performance advantage, as you'd normally use the term. Instead, it gives access to data stored in structures that aren't accessible in other ways.
Looking specifically at forward iterator, it can be used (for one example) for accessing data stored in a singly linked list, where a bidirectional iterator would normally require a doubly linked list.
Using a singly linked list could lead to a performance advantage over a doubly linked list--it only requires one pointer per node instead of two. With fewer pointers per node, you can typically expect to store more nodes in the cache, which can improve performance (considerably) by requiring fewer references to main memory.
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
answered Nov 10 at 16:13
Jerry Coffin
380k48459899
380k48459899
add a comment |
add a comment |
1
Your question doesn't make sense. Who is the "you" in this scenario? Are you designing a container or iterator? Are you writing an algorithm that consumes iterators? And what makes you think that "ForwardIterator" has anything to do with performance (or at least, in the way you mean it)?
– Nicol Bolas
Nov 10 at 16:02
There aren't any -- every Bidi iterator is a forward iterator, and every random-access iterator is bidi. So you can do strictly more with the stronger guarantees. Usually when something is a forward iterator, that's because that's the best it can be.
– Kerrek SB
Nov 10 at 16:02
you have the question reversed. instead you shuold ask yourself: why would i use a bidirectional iterator, when i need to iterate only in forward direction? ... and the answer is: you dont
– user463035818
Nov 10 at 16:07