Hi,
Does STL and Vector provide the default sorting option?.
+6
A:
You probably want std::sort.
#include <algorithm>
#include <vector>
int
main()
{
std::vector<int> foo;
std::sort( foo.begin(), foo.end() );
return 0;
}
a similar example using two boost libraries is below.
#include <boost/assign/list_of.hpp>
#include <boost/foreach.hpp>
#include <algorithm>
#include <iostream>
#include <vector>
int
main()
{
std::vector<int> foo = boost::assign::list_of(1)(4)(5)(10)(3)(2);
std::cout << "unsorted" << std::endl;
BOOST_FOREACH( const int i, foo ) {
std::cout << i << std::endl;
}
std::sort( foo.begin(), foo.end() );
std::cout << "sorted" << std::endl;
BOOST_FOREACH( const int i, foo ) {
std::cout << i << std::endl;
}
return 0;
}
Sam Miller
2010-06-21 12:22:05
I think your code example would be better if you stuck to the basics. Requiring the reader to be familiar with two different Boost libraries just to understand a `std::sort` example might be a bit much to ask.
jalf
2010-06-21 12:27:25
For simple case, like sorting using boost is most likely not justified.
Wojtek
2010-06-21 12:42:11
I think you are over reacting - the two Boost constructs used here are extremely easy to understand, even for a complete beginner to Boost (which I am). Their use was not necessary - in fact simply having the `std::sort( beginIndex, endIndex )` line would have been enough - but they hardly "require the reader to be familiar with two Boost libraries".
jhominal
2010-06-21 14:14:38
@jhominal: I'm not overreacting, I'm just saying the example is less clear than it could have been. I didn't say it is unreadable as it is now, just suggesting an improvement. :)
jalf
2010-06-21 14:49:11
list_of and foreach are just scratching the surface of boost, you need not be familiar with the entire library to understand what they accomplish. A C++ programmer completely unfamiliar with boost should be able to easily grasp the concepts presented in my example.Unilaterally declaring any use of boost as unnecessary in such a trivial example is why some beginners shy away from using it. Yes it can be intimidating, but the example here shows otherwise.
Sam Miller
2010-06-21 15:24:19
@samm: when I look for an example of how to do something, I prefer to see a *minimal* example: something with as little noise as possible, which makes no assumptions about the surrounding code. Yes, I can easily read your code, and I am familiar with both the libs you use. But there is a lot more code for me to read through and mentally parse in order to see how much of this is actually *necessary*. If you want more people to use Boost (which is a good thing), I don't think turning what could be a one-liner into 18 lines of code is the right way to do it.
jalf
2010-06-21 21:07:09
I've added an example without using boost.
Sam Miller
2010-06-22 03:32:58
+11
A:
Yes, there is sort() in stl algorithms. You should look at http://www.cplusplus.com/reference/algorithm/sort/
Mewp
2010-06-21 12:22:16
@Shadow: Sure. For example: `std::sort(vec.begin(),vec.end(),std::greater<int>());`, see `<algorithm>` and `<functional>`
sellibitze
2010-06-21 13:34:50
+23
A:
The vector class doesn't have a sort function.
But there is a sort which works on all iterator ranges. And vector does expose iterators.
To sort a vector vec:
#include <algorithm>
std::sort(vec.begin(), vec.end());
jalf
2010-06-21 12:25:52
This is what you'll want to do, Boost is absolutely NOT necessary for this whatsoever.
rubenvb
2010-06-21 12:35:56
Not all containers - only those with random access. `list` has a member function `sort`, ordered associative containers are already sorted, and unordered associative containers can't be sorted.
Mike Seymour
2010-06-21 12:37:24
For completeness, you could mention that it is possible to specify _how_ it should be sorted as well.
Mattias Nilsson
2010-06-21 12:38:17
@Mike: true, of course. I edited my answer. I just didn't want to go into too much detail about iterators since the OP might not be familiar with them.
jalf
2010-06-21 12:41:28
@Mattias: true, but the OP has said nothing to indicate that he needs this. If he does, I'll edit it in.
jalf
2010-06-21 12:42:46
+1
A:
As other's have mentioned in their answers, there is std::sort function.
However, by "the default sorting option?." do you mean you want to sort a vector where T is a class you have defined. In that case, you have to implement "operator<" in your class.
For example,
class Foo
{
public :
Foo();
~Foo();
private :
int c;
};
std::vector<Foo> foovec;
std::sort(foovec.begin(), foovec.end());
To make sure that above "std::sort" line works, you need to define "operator<" in Foo.
class Foo
{
public :
Foo();
~Foo();
bool operator<(const Foo& rFoo) const;
private :
int c;
};
bool Foo::operator<(const Foo& rFoo) const
{
return(c < rFoo.c);
}
Nitin Bhide
2010-06-21 14:02:48