錯誤：c ++ [map]沒有命名類型

Question

我已經將以下內容編寫為文本冒險游戲的文本命令解析器的一部分。

我試圖將用戶輸入的字符串與枚舉類中的項相關聯。 以下是我的頭文件：

#include <iostream>
#include <map>
#include <string>
using namespace std;

enum class Noun
{
    // Interrogation subjects
    name,                   // ask the subject his name
    base,                   // where is the base?
    attack,                 // when will the attack be?

    invalid
};

map < string, Noun > knownNouns;
knownNouns["name"]      = Noun::name;
knownNouns["base"]      = Noun::base;
knownNouns["attack"]    = Noun::attack;

Noun parseNoun(string &noun)
{
    auto n = knownNouns.find(noun);
    if ( n == knownNouns.end() ) {
        return Noun::invalid;
    }
    return n->second;

當我通過編譯器，我得到以下內容：

nouns.h:46:1: error: 'knownNouns' does not name a type
 knownNouns["name"]      = Noun::name;
 ^
nouns.h:47:1: error: 'knownNouns' does not name a type
 knownNouns["base"]      = Noun::base;
 ^
nouns.h:48:1: error: 'knownNouns' does not name a type
 knownNouns["attack"]    = Noun::attack;
 ^
nouns.h: In function 'Noun parseNoun(std::string&)':
nouns.h:52:10: error: 'n' does not name a type
     auto n = knownNouns.find(noun);
          ^
nouns.h:53:10: error: 'n' was not declared in this scope
     if ( n == knownNouns.end() ) {
          ^
nouns.h:54:16: error: 'Noun' is not a class or namespace
         return Noun::invalid;
                ^
nouns.h:56:12: error: 'n' was not declared in this scope
     return n->second;
            ^

這是我第一次嘗試使用地圖和枚舉，而且我不確定我做錯了什么。 我對自動變速器的使用也不是非常熟悉，所以這對我來說是一些貨物狂熱編程。 我希望我理解它的實現，一旦我解決了我遇到的類型定義問題，錯誤就會清除。

編輯：這很令人尷尬。 我復制粘貼了一個我已經糾正過的錯誤。 代碼仍然無法編譯時（即，同樣的問題出現時）

map < string, Noun > knownNouns;
knownNouns["name"]      = Verb::name;
knownNouns["base"]      = Verb::base;
knownNouns["attack"]    = Verb::attack;

被糾正為

map < string, Noun > knownNouns;
knownNouns["name"]      = Noun::name;
knownNouns["base"]      = Noun::base;
knownNouns["attack"]    = Noun::attack;

Answer 1

您不能將非聲明構造直接放在命名空間范圍中。

C ++翻譯單元是一系列聲明。

分配等非聲明語句必須在函數體內。

---

固定代碼：

#include <iostream>
#include <map>
#include <string>
using namespace std;

enum class Noun
{
    // Interrogation subjects
    name,                   // ask the subject his name
    base,                   // where is the base?
    attack,                 // when will the attack be?

    invalid
};

map< string, Noun > knownNouns = 
{
    { "name", Noun::name },
    { "base", Noun::base },
    { "attack", Noun::attack }
};

auto parseNoun( string const& noun )
    -> Noun
{
    // auto n = knownNouns.find(noun);
    // if ( n == knownNouns.end() ) {
        // return Noun::invalid;
    // }
    // return n->second;
    return Noun::invalid;
}

這里knownNouns已初始化 。 它不是一個任務，即使=看起來非常像一個任務。

Answer 2

您可能無法靜態初始化地圖條目，如：

 knownNouns["name"]      = Verb::name;
 knownNouns["base"]      = Verb::base;
 knownNouns["attack"]    = Verb::attack;