std::equal_range huycwork的日志 网易博客

std::equal_range - huycwork的日志 - 网易博客

equal_range

原型:

 #include <algorithm>
 pair<forward_iterator,forward_iterator> equal_range( forward_iterator first, forward_iterator last, const TYPE& val );
 pair<forward_iterator,forward_iterator> equal_range( forward_iterator first, forward_iterator last, const TYPE& val, CompFn comp );

函数equal_range()返回first和last之间等于val的元素区间. 此函数假定first和last区间内的元素可以使用<操作符或者指定的comp执行比较操作.

equal_range()可以被认为是lower_bound和upper_bound的结合, pair中的第一个迭代器由lower_bound返回, 第二个则由upper_bound返回.

例如, 下面的代码使用equal_range()探测一个有序的vector中的可以插入数字8的位置:

 vector<int> nums;
 nums.push_back( -242 );
 nums.push_back( -1 );
 nums.push_back( 0 );
 nums.push_back( 5 );
 nums.push_back( 8 );
 nums.push_back( 8 );
 nums.push_back( 11 );
 pair<vector<int>::iterator, vector<int>::iterator> result;
 int new_val = 8;  
 result = equal_range( nums.begin(), nums.end(), new_val ); 
 cout
 << "The first place that " << new_val
 << " could be inserted is before " << *result.first
 << ", and the last place that it could be inserted is before " << *result.second
 << endl;

上面的代码将产生如下输出:

 The first place that 8 could be inserted is before 8, and the last place that it could be inserted is before 11

相关主题: binary_search, lower_bound, upper_bound