unique (<algorithm>)
移除相互靠近的位于指定范围的元素复制。
template<class ForwardIterator>
ForwardIterator unique(
ForwardIterator _First,
ForwardIterator _Last
);
template<class ForwardIterator, class Predicate>
ForwardIterator unique(
ForwardIterator _First,
ForwardIterator _Last,
Predicate _Comp
);
参数
_First
处理第一元素的位置将向前迭代器在用于复制删除将扫描的范围。_Last
寻址最终元素的前向迭代器位置一个对复制删除将扫描的范围。_Comp
定义将满足的条件的用户定义的谓词函数对象,如果两个元素将采用为相等。 二进制谓词采用两个参数,并且在满足时返回 true,在未满足时返回 false。
返回值
对包含不运行的副本。修改序列的新的末尾的前向迭代器,寻址没有移除的最后的元素位置。
备注
算法的两窗体移除一个连续对的第二个副本相等元素。
算法的操作是稳定,以便被撤消删除元素的相对顺序不会更改。
引用的范围必须是有效的;所有指针必须 dereferenceable,然后在序列中的最后位置从开始来访问通过递增。他在计算序列的元素不是由 unique 更改算法,并超出已修改的序列。结束的元素是 dereferenceable,但没有指定。
复杂线性的,需要 (_Last - _First) - 1 进行比较。
列表提供更高效的成员函数 唯一,可能更好执行。
这些算法在一个容器关联无法使用。
示例
// alg_unique.cpp
// compile with: /EHsc
#include <vector>
#include <algorithm>
#include <functional>
#include <iostream>
#include <ostream>
using namespace std;
// Return whether modulus of elem1 is equal to modulus of elem2
bool mod_equal ( int elem1, int elem2 )
{
if ( elem1 < 0 )
elem1 = - elem1;
if ( elem2 < 0 )
elem2 = - elem2;
return elem1 == elem2;
};
int main( )
{
vector <int> v1;
vector <int>::iterator v1_Iter1, v1_Iter2, v1_Iter3,
v1_NewEnd1, v1_NewEnd2, v1_NewEnd3;
int i;
for ( i = 0 ; i <= 3 ; i++ )
{
v1.push_back( 5 );
v1.push_back( -5 );
}
int ii;
for ( ii = 0 ; ii <= 3 ; ii++ )
{
v1.push_back( 4 );
}
v1.push_back( 7 );
cout << "Vector v1 is ( " ;
for ( v1_Iter1 = v1.begin( ) ; v1_Iter1 != v1.end( ) ; v1_Iter1++ )
cout << *v1_Iter1 << " ";
cout << ")." << endl;
// Remove consecutive duplicates
v1_NewEnd1 = unique ( v1.begin ( ) , v1.end ( ) );
cout << "Removing adjacent duplicates from vector v1 gives\n ( " ;
for ( v1_Iter1 = v1.begin( ) ; v1_Iter1 != v1_NewEnd1 ; v1_Iter1++ )
cout << *v1_Iter1 << " ";
cout << ")." << endl;
// Remove consecutive duplicates under the binary prediate mod_equals
v1_NewEnd2 = unique ( v1.begin ( ) , v1_NewEnd1 , mod_equal );
cout << "Removing adjacent duplicates from vector v1 under the\n "
<< " binary predicate mod_equal gives\n ( " ;
for ( v1_Iter2 = v1.begin( ) ; v1_Iter2 != v1_NewEnd2 ; v1_Iter2++ )
cout << *v1_Iter2 << " ";
cout << ")." << endl;
// Remove elements if preceded by an element that was greater
v1_NewEnd3 = unique ( v1.begin ( ) , v1_NewEnd2, greater<int>( ) );
cout << "Removing adjacent elements satisfying the binary\n "
<< " predicate mod_equal from vector v1 gives ( " ;
for ( v1_Iter3 = v1.begin( ) ; v1_Iter3 != v1_NewEnd3 ; v1_Iter3++ )
cout << *v1_Iter3 << " ";
cout << ")." << endl;
}
要求
标头: <算法>
命名空间: std