方法/步骤 1 打开Arcmap,我这里又点point、线line、面polygon、面polygonB四个图层。在点point、线line、面polygon分别有图形显示如下图：2 然后在面polygonB中画一个擦除层，这里就画一个长方形作为参照。3 点击ArcToolbox，打开ArcToolbox工具箱，找到下面的erase工具。4 双击erase，打开erase对话框。在对话框...
{ std::map<int, char> data { {1, 'a'}, {2, 'b'}, {3, 'c'}, {4, 'd'}, {5, 'e'}, {4, 'f'}, {5, 'g'}, {5, 'g'}, }; println("Original:\n", data); const auto count = std::erase_if(data, [](const auto& item) { auto const& [key, value] = item...
map<int,double,greater<int> > mp;intmain(){ mp[1]=10; mp[2]=100;for(autoit=mp.begin(); it!=mp.end(); it++){if(it->ft==1) mp.erase(it); }return0; } 改成这样就不会了 #include<bits/stdc++.h>#defineft first#definesd secondusingnamespacestd; map<int,double,greater<int>...
#include <iostream> #include <map> void println(auto rem, auto const& container) { std::cout << rem << '{'; for (char sep[]{0, ' ', 0}; const auto& [key, value] : container) std::cout << sep << '{' << key << ", " << value << '}', *sep = ','; std::cou...
这种情况一般是线程未同步引起的。STL不是线程安全的，如果你在多个线程中同时操作同一个map，你就必须自己进行同步。
map(m1); // The 1st member function removes an element at a given position m1.erase(next(m1.begin())); cout << "After the 2nd element is deleted, the map m1 is:" << endl; printmap(m1); // Fill in some data to test with, one at a time, using an intializer list mymap ...
unordered_map<string, int > my_map; // ... 向 my_map 中插入一些数据 my_map.erase("key"); ``` 其中,"key"是要删除的键。如果"key"不存在于`my_map`中,那么`erase`方法不会有任何作用。 此外,`erase`方法还可以接受一个迭代器作为参数,删除迭代器指向的元素,并返回下一个元素的迭代器。例如...
从1中,我们可以看到erase的返回值是iterator。An iterator pointing to the element that followed the last element erased by the function call(指向erase元素的后一个元素的迭代器)。 于是我们有了以下清除方法: 1#include"Allinclude.h"23intmain()4{56cout<<endl<<"map:"<<endl;7map<char,int>mymap;...
void Remove4(std::map<int, int>& maps) std::map<int, int>::iterator iter = maps.begin(); while (iter != maps.end()) if (0 == (iter->first)%2) maps.erase(iter++); else ++iter; set和map是由红黑树来实现的,当erase的时候迭代器就失效了,也就是说我们要在迭代器失效之前保留一个...
The first member function removes the element of the controlled sequence pointed to by where, and returns an iterator that designates the first element remaining beyond the element removed, or map::end (STL/CLR)() if no such element exists. You use it to remove a single element....