foreach在C ++中不被识别 [英] foreach not recognized in C++

问题描述

在我的cs106b书中，我们使用表达式foreach来查看Map中的单词列表。我执行了代码，把我的头撞在了面对神秘错误的墙上。代码如下：
$ b $ $ pre $ void $ DisplayWordCounts（Map< int>& wordsCount）{
foreach（字串中的字数） ）{
cout<<左<< （15）<字<<正确<< （5）
<< wordsCount [word]<< ENDL;


$ / code>

以foreach开头以下错误：
lesson4-macbeth / life.cpp：58：错误：期望在word之前的主要表达式
lesson4-macbeth / life.cpp：58：错误：'foreach'未被声明这个范围
lesson4-macbeth / life.cpp：58：error：expected`;'before'{'token

我猜foreach是不被识别的。在这种情况下，我怎样才能通过Map类的项目列表？

解决方案 不是标准的C ++特性。我实际上帮助Eric Roberts把CS106B / X的实现放在一起，如果你 #includeforeach.h，你应该可以使用它。如果你好奇，我可以尝试发送你的文件的源代码。

另外，找到堆栈溢出的道具！虽然你的SL应该可能是你的第一道防线。 ： - ）

In my the cs106b book we use the expression "foreach" to go through a list of words in a Map. I implemented the code and banged my head against the wall facing mysterious errors. Here's the code:

   void DisplayWordCounts(Map<int> & wordsCount) {
     foreach (string word in wordsCount) {
        cout << left << setw(15) << word << right << setw(5)
        << wordsCount[word] << endl;
     }
}

on the line starting with "foreach" I get the following errors: lesson4-macbeth/life.cpp:58: error: expected primary-expression before 'word' lesson4-macbeth/life.cpp:58: error: 'foreach' was not declared in this scope lesson4-macbeth/life.cpp:58: error: expected `;' before '{' token

I guess foreach is not recognized. In that case, how can I go through a list of items from the Map class?

解决方案

foreach is not a standard C++ feature. I actually helped Eric Roberts put together the implementation for CS106B/X, and you should be able to use it if you #include "foreach.h". If you're curious, I can try to send you the file's source code.

Also, props for finding Stack Overflow! Though your SL should probably be your first line of defense. :-)

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