Difference between BOOST_FOREACH and c++11 for range based loop?
- What are the main differences between
BOOST_FOREACHand c++11 range based loop? - Is there a specific situation where I would want to use
BOOST_FOREACHinstead of range based loop or vice versa?
After executing a little test with std::vector filled with 1,000,000 int variables I found out that BOOST_FOREACH is a little bit slower than range based loop (took about 1.25 times longer than for a ranged based loop).
c++ c++11 boost foreach
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
add a comment |
- What are the main differences between
BOOST_FOREACHand c++11 range based loop? - Is there a specific situation where I would want to use
BOOST_FOREACHinstead of range based loop or vice versa?
After executing a little test with std::vector filled with 1,000,000 int variables I found out that BOOST_FOREACH is a little bit slower than range based loop (took about 1.25 times longer than for a ranged based loop).
c++ c++11 boost foreach
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
I'm not sure that there is a use forboost::foreachin new code anymore. I think it's only useful in old code, before there were ranged-based loops.
– Mooing Duck
Nov 19 '14 at 21:50
Do you meanBOOST_FOREACH?
– Barry
Nov 19 '14 at 21:52
@Barry Yes, I do. Let me edit that.
– Laurynas Lazauskas
Nov 19 '14 at 21:53
add a comment |
- What are the main differences between
BOOST_FOREACHand c++11 range based loop? - Is there a specific situation where I would want to use
BOOST_FOREACHinstead of range based loop or vice versa?
After executing a little test with std::vector filled with 1,000,000 int variables I found out that BOOST_FOREACH is a little bit slower than range based loop (took about 1.25 times longer than for a ranged based loop).
c++ c++11 boost foreach
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
- What are the main differences between
BOOST_FOREACHand c++11 range based loop? - Is there a specific situation where I would want to use
BOOST_FOREACHinstead of range based loop or vice versa?
After executing a little test with std::vector filled with 1,000,000 int variables I found out that BOOST_FOREACH is a little bit slower than range based loop (took about 1.25 times longer than for a ranged based loop).
c++ c++11 boost foreach
c++ c++11 boost foreach
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
edited Nov 19 '14 at 21:54
Laurynas Lazauskas
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
asked Nov 19 '14 at 21:47
Laurynas LazauskasLaurynas Lazauskas
6921916
6921916
I'm not sure that there is a use forboost::foreachin new code anymore. I think it's only useful in old code, before there were ranged-based loops.
– Mooing Duck
Nov 19 '14 at 21:50
Do you meanBOOST_FOREACH?
– Barry
Nov 19 '14 at 21:52
@Barry Yes, I do. Let me edit that.
– Laurynas Lazauskas
Nov 19 '14 at 21:53
add a comment |
I'm not sure that there is a use forboost::foreachin new code anymore. I think it's only useful in old code, before there were ranged-based loops.
– Mooing Duck
Nov 19 '14 at 21:50
Do you meanBOOST_FOREACH?
– Barry
Nov 19 '14 at 21:52
@Barry Yes, I do. Let me edit that.
– Laurynas Lazauskas
Nov 19 '14 at 21:53
I'm not sure that there is a use for
boost::foreach in new code anymore. I think it's only useful in old code, before there were ranged-based loops.– Mooing Duck
Nov 19 '14 at 21:50
I'm not sure that there is a use for
boost::foreach in new code anymore. I think it's only useful in old code, before there were ranged-based loops.– Mooing Duck
Nov 19 '14 at 21:50
Do you mean
BOOST_FOREACH?– Barry
Nov 19 '14 at 21:52
Do you mean
BOOST_FOREACH?– Barry
Nov 19 '14 at 21:52
@Barry Yes, I do. Let me edit that.
– Laurynas Lazauskas
Nov 19 '14 at 21:53
@Barry Yes, I do. Let me edit that.
– Laurynas Lazauskas
Nov 19 '14 at 21:53
add a comment |
2 Answers
2
active
oldest
votes
The main difference is that range-for is a language construct, while BOOST_FOREACH is a macro doing lots of magic under the hood to do something that looks like that language construct. It is trying to do exactly the same thing with the limitations of pre-C++11. The goal of BOOST_FOREACH is range-for.
There is exactly one situation where I would even think of using BOOST_FOREACH instead of range-for, and it is iterating over a container of tuples where you want to unroll the tuple:
std::map<int, int> m;
int key, value;
BOOST_FOREACH(boost::tie(key, value), m)
{
// do something with key and value here
}
as compared to:
int key, value;
for (const auto& pair : m)
{
std::tie(key, value) = pair;
// do something
}
I like that you can put the tie directly into the loop header, although ultimately that's such a minor advantage that it's hardly worth even considering this as being a decision. Use range-for. Always.
C++17 will introduce structured bindings, which remove even that minor syntactical advantage:
for (auto const& [key, value] : m)
{
// do something
}
At that point, there will be no reason whatsoever to use BOOST_FOREACH.
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
Nice trick with std::tie and boost_foreach :)
– Viktor Sehr
Nov 19 '18 at 16:08
add a comment |
boost offers BOOST_REVERSE_FOREACH which allows you to traverse containers backwards. The for ranged loop does not provide an similar functionality.
answered Nov 19 '18 at 15:35
CatrielCatriel
14
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
The main difference is that range-for is a language construct, while BOOST_FOREACH is a macro doing lots of magic under the hood to do something that looks like that language construct. It is trying to do exactly the same thing with the limitations of pre-C++11. The goal of BOOST_FOREACH is range-for.
There is exactly one situation where I would even think of using BOOST_FOREACH instead of range-for, and it is iterating over a container of tuples where you want to unroll the tuple:
std::map<int, int> m;
int key, value;
BOOST_FOREACH(boost::tie(key, value), m)
{
// do something with key and value here
}
as compared to:
int key, value;
for (const auto& pair : m)
{
std::tie(key, value) = pair;
// do something
}
I like that you can put the tie directly into the loop header, although ultimately that's such a minor advantage that it's hardly worth even considering this as being a decision. Use range-for. Always.
C++17 will introduce structured bindings, which remove even that minor syntactical advantage:
for (auto const& [key, value] : m)
{
// do something
}
At that point, there will be no reason whatsoever to use BOOST_FOREACH.
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
Nice trick with std::tie and boost_foreach :)
– Viktor Sehr
Nov 19 '18 at 16:08
add a comment |
The main difference is that range-for is a language construct, while BOOST_FOREACH is a macro doing lots of magic under the hood to do something that looks like that language construct. It is trying to do exactly the same thing with the limitations of pre-C++11. The goal of BOOST_FOREACH is range-for.
There is exactly one situation where I would even think of using BOOST_FOREACH instead of range-for, and it is iterating over a container of tuples where you want to unroll the tuple:
std::map<int, int> m;
int key, value;
BOOST_FOREACH(boost::tie(key, value), m)
{
// do something with key and value here
}
as compared to:
int key, value;
for (const auto& pair : m)
{
std::tie(key, value) = pair;
// do something
}
I like that you can put the tie directly into the loop header, although ultimately that's such a minor advantage that it's hardly worth even considering this as being a decision. Use range-for. Always.
C++17 will introduce structured bindings, which remove even that minor syntactical advantage:
for (auto const& [key, value] : m)
{
// do something
}
At that point, there will be no reason whatsoever to use BOOST_FOREACH.
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
Nice trick with std::tie and boost_foreach :)
– Viktor Sehr
Nov 19 '18 at 16:08
add a comment |
The main difference is that range-for is a language construct, while BOOST_FOREACH is a macro doing lots of magic under the hood to do something that looks like that language construct. It is trying to do exactly the same thing with the limitations of pre-C++11. The goal of BOOST_FOREACH is range-for.
There is exactly one situation where I would even think of using BOOST_FOREACH instead of range-for, and it is iterating over a container of tuples where you want to unroll the tuple:
std::map<int, int> m;
int key, value;
BOOST_FOREACH(boost::tie(key, value), m)
{
// do something with key and value here
}
as compared to:
int key, value;
for (const auto& pair : m)
{
std::tie(key, value) = pair;
// do something
}
I like that you can put the tie directly into the loop header, although ultimately that's such a minor advantage that it's hardly worth even considering this as being a decision. Use range-for. Always.
C++17 will introduce structured bindings, which remove even that minor syntactical advantage:
for (auto const& [key, value] : m)
{
// do something
}
At that point, there will be no reason whatsoever to use BOOST_FOREACH.
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
The main difference is that range-for is a language construct, while BOOST_FOREACH is a macro doing lots of magic under the hood to do something that looks like that language construct. It is trying to do exactly the same thing with the limitations of pre-C++11. The goal of BOOST_FOREACH is range-for.
There is exactly one situation where I would even think of using BOOST_FOREACH instead of range-for, and it is iterating over a container of tuples where you want to unroll the tuple:
std::map<int, int> m;
int key, value;
BOOST_FOREACH(boost::tie(key, value), m)
{
// do something with key and value here
}
as compared to:
int key, value;
for (const auto& pair : m)
{
std::tie(key, value) = pair;
// do something
}
I like that you can put the tie directly into the loop header, although ultimately that's such a minor advantage that it's hardly worth even considering this as being a decision. Use range-for. Always.
C++17 will introduce structured bindings, which remove even that minor syntactical advantage:
for (auto const& [key, value] : m)
{
// do something
}
At that point, there will be no reason whatsoever to use BOOST_FOREACH.
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
edited Sep 9 '17 at 8:53
Rakete1111
34.6k1082118
34.6k1082118
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
answered Nov 19 '14 at 21:58
BarryBarry
181k19315576
181k19315576
Nice trick with std::tie and boost_foreach :)
– Viktor Sehr
Nov 19 '18 at 16:08
add a comment |
Nice trick with std::tie and boost_foreach :)
– Viktor Sehr
Nov 19 '18 at 16:08
Nice trick with std::tie and boost_foreach :)
– Viktor Sehr
Nov 19 '18 at 16:08
Nice trick with std::tie and boost_foreach :)
– Viktor Sehr
Nov 19 '18 at 16:08
add a comment |
boost offers BOOST_REVERSE_FOREACH which allows you to traverse containers backwards. The for ranged loop does not provide an similar functionality.
answered Nov 19 '18 at 15:35
CatrielCatriel
14
add a comment |
boost offers BOOST_REVERSE_FOREACH which allows you to traverse containers backwards. The for ranged loop does not provide an similar functionality.
answered Nov 19 '18 at 15:35
CatrielCatriel
14
add a comment |
boost offers BOOST_REVERSE_FOREACH which allows you to traverse containers backwards. The for ranged loop does not provide an similar functionality.
answered Nov 19 '18 at 15:35
CatrielCatriel
14
boost offers BOOST_REVERSE_FOREACH which allows you to traverse containers backwards. The for ranged loop does not provide an similar functionality.
answered Nov 19 '18 at 15:35
CatrielCatriel
14
answered Nov 19 '18 at 15:35
CatrielCatriel
14
answered Nov 19 '18 at 15:35
CatrielCatriel
14
answered Nov 19 '18 at 15:35
CatrielCatriel
14
14
add a comment |
add a comment |
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I'm not sure that there is a use for
boost::foreachin new code anymore. I think it's only useful in old code, before there were ranged-based loops.– Mooing Duck
Nov 19 '14 at 21:50
Do you mean
BOOST_FOREACH?– Barry
Nov 19 '14 at 21:52
@Barry Yes, I do. Let me edit that.
– Laurynas Lazauskas
Nov 19 '14 at 21:53