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Front Page / Iterators / Iterator Metafunctions / advance |
Moves Iterator by the distance N. For bidirectional and random access iterators, the distance may be negative.
#include <boost/mpl/advance.hpp>
Parameter | Requirement | Description |
---|---|---|
Iterator | Forward Iterator | An iterator to advance. |
N | Integral Constant | A distance. |
For a Forward Iterator iter and arbitrary Integral Constant n:
typedef advance<iter,n>::type j;
Return type: | |
---|---|
Precondition: | If Iterator is a Forward Iterator, n::value must be nonnegative. |
Semantics: | Equivalent to: typedef iter i0; typedef next<i0>::type i1; ... typedef next<in-1>::type j; if n::value > 0, and typedef iter i0; typedef prior<i0>::type i1; ... typedef prior<in-1>::type j; otherwise. |
Postcondition: | j is dereferenceable or past-the-end; distance<iter,j>::value == n::value if n::value > 0, and distance<j,iter>::value == n::value otherwise. |
Amortized constant time if iter is a model of Random Access Iterator, otherwise linear time.
typedef range_c<int,0,10> numbers; typedef begin<numbers>::type first; typedef end<numbers>::type last; typedef advance<first,int_<10> >::type i1; typedef advance<last,int_<-10> >::type i2; BOOST_MPL_ASSERT(( boost::is_same<i1,last> )); BOOST_MPL_ASSERT(( boost::is_same<i2,first> ));