我需要打印一个包含多图的dequeu,但它不起作用,我做错了什么?
int main()
{
deque<multimap<string,int> > q_map;
multimap<string,int> m;
m.insert(pair<string, int>("a", 1));
m.insert(pair<string, int>("c", 2));
m.insert(pair<string, int>("b", 3));
m.insert(pair<string, int>("b", 4));
m.insert(pair<string, int>("a", 5));
m.insert(pair<string, int>("b", 6));
cout << "Map size: " << m.size() << endl;
q_map.push_back(m);
for (std::deque<int>::iterator it = q_map.begin(); it!=q_map.end(); ++it)
std::cout << ' ' << *it;
}
我总是遇到编译错误:
error: conversion from ‘std::_Deque_iterator<std::multimap<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> > >, std::multimap<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> > >&, std::multimap<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> > >*>’ to non-scalar type ‘std::_Deque_iterator<int, int&, int*>’ requested
q_map.cpp:23: error: no match for ‘operator!=’ in ‘it != std::deque<_Tp, _Alloc>::end() [with _Tp = std::multimap<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> > >, _Alloc = std::allocator<std::multimap<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> > > >]()’
答案 0 :(得分:1)
好吧,两个简单的for循环,一个迭代deque
,另一个迭代multimap
:
for ( auto it = q_map.begin(); it != q_map.end(); ++it )
for ( auto it2 = (*it).begin(); it2 != (*it).end(); ++it2 )
cout << ' ' << it2->first << ' ' << it2->second << endl;
或使用范围循环
for ( auto& it : q_map )
for ( auto& it2 : it )
cout << ' ' << it2.first << ' ' << it2.second << endl;
答案 1 :(得分:0)
你有这种类型:
deque<multimap<string,int> > q_map;
但是你正试图用这种类型迭代它:
for (std::deque<int>::iterator it = q_map.begin(); ...
那是你做错了什么。
如果您不能使用基于C ++ 11范围的for
循环或C ++ 11 auto
功能,那么请不要重复multimap<string,int>
类型无处不在,你可以使用typedef:
typedef multimap<string,int> mmap;
现在,您可以在使用它的任何地方引用std::deque<mmap>
,因此for
循环将使用std::deque<mmap>::iterator