View Compilation Error

0_0_24171711_20408.cpp: In function 'int main()':
0_0_24171711_20408.cpp:31:4: error: 'lib' is not a class, namespace, or enumeration
    lib::iterator it = lib.find(key);
    ^
0_0_24171711_20408.cpp:32:13: error: 'it' was not declared in this scope
    cout << (it == lib.end() ? key : it->second);//没查到输出空字符串  所以dev里面map的迭代器到底提示的是啥玩意? 
             ^