map<string, int> M;
for (auto E: M)
{
cout << E.first << ": " << E.second << endl;
F << E.first << ": " << E.second << endl;
};
我正在学习C ,我与自动感到困惑。我正在尝试将上述代码转换为以下代码(上面具有自动工作的代码正确(
map<string, int> M;
for (map<string, int> :: iterator p = begin(M); p != end(M); p ++ )
{
cout << p.first << ": " << p.second << endl;
F << p.first << ": " << p.second << endl;
}
我有以下错误:
error: ‘std::map<std::basic_string<char>, int>::iterator’ has no member named ‘first’
cout << p.first << ": " << p.second << endl;
error: ‘std::map<std::basic_string<char>, int>::iterator’ has no member named ‘second’
cout << p.first << ": " << p.second << endl;
error: ‘std::map<std::basic_string<char>, int>::iterator’ has no member named ‘first’
F << p.first << ": " << p.second << endl;
error: ‘std::map<std::basic_string<char>, int>::iterator’ has no member named ‘second’
F << p.first << ": " << p.second << endl;
为什么它不起作用?
迭代器就像指针一样,必须使用:
cout << p->first << ": " << p->second << endl;
远程循环( auto
的示例(为您做到了。