Goto 变量初始化之前导致编译器错误

考虑这段代码（VS2008）：

void WordManager::formatWords(std::string const& document)
{
    document_ = document;
    unsigned int currentLineNo = 1;

    size_t oldEndOfLine = 0;
    size_t endOfLine    = document_.find('\n');
    while(endOfLine != std::string::npos)
    {
        std::string line = document_.substr(oldEndOfLine, (endOfLine - oldEndOfLine));
        if(line.size() < 2)
        {
            oldEndOfLine = endOfLine + 1;
            endOfLine    = document_.find('\n', oldEndOfLine);
            continue;
        }

        std::vector<std::string> words = Utility::split(line);
        for(unsigned int i(0); i < words.size(); ++i)
        {
            if(words[i].size() < 2)
                continue;
            Utility::trim(words[i], WordManager::delims);
            Utility::normalize(words[i], WordManager::replace, WordManager::replaceWith);

            if(ruleOne(words[i]) && ruleTwo(words[i]))
            {
                std::set<Word>::iterator sWIter(words_.find(Word(words[i])));

                if(sWIter == words_.end())
                    words_.insert(Word(words[i])).first->addLineNo(currentLineNo);
                else
                    sWIter->addLineNo(currentLineNo);
            }
        }
        ++currentLineNo;

        oldEndOfLine = endOfLine + 1;
        endOfLine    = document_.find('\n', oldEndOfLine);
    }
}

如果它很重要：这是家庭作业中的代码，用于过滤和修改文档中的单词。document保存文档（之前从文件中读取）

我希望引入一个恶意 goto，因为我认为在这种情况下它实际上更干净，如下所示：

void WordManager::formatWords(std::string const& document)
{
    document_ = document;
    unsigned int currentLineNo = 1;

    size_t oldEndOfLine = 0;
    size_t endOfLine    = document_.find('\n');
    while(endOfLine != std::string::npos)
    {
        std::string line = document_.substr(oldEndOfLine, (endOfLine - oldEndOfLine));
        // HERE!!!!!!
        if(line.size() < 2)
            goto SkipAndRestart;

        std::vector<std::string> words = Utility::split(line);
        for(unsigned int i(0); i < words.size(); ++i)
        {
            if(words[i].size() < 2)
                continue;
            Utility::trim(words[i], WordManager::delims);
            Utility::normalize(words[i], WordManager::replace, WordManager::replaceWith);

            if(ruleOne(words[i]) && ruleTwo(words[i]))
            {
                std::set<Word>::iterator sWIter(words_.find(Word(words[i])));

                if(sWIter == words_.end())
                    words_.insert(Word(words[i])).first->addLineNo(currentLineNo);
                else
                    sWIter->addLineNo(currentLineNo);
            }
        }

SkipAndRestart:
        ++currentLineNo;

        oldEndOfLine = endOfLine + 1;
        endOfLine    = document_.find('\n', oldEndOfLine);
    }
}

这是否是一个好的设计选择目前并不重要。编译器抱怨error C2362: initialization of 'words' is skipped by 'goto SkipAndRestart'

我不明白这个错误。为什么跳过初始化这个词很重要，而且是一个错误？这正是我想要发生的，我不想让它做更多的工作，只是重新开始该死的循环。 continue 宏不是做或多或少完全相同的事情吗？

您正在跳过的构建words array:

    if(line.size() < 2)
        goto SkipAndRestart;
    std::vector<std::string> words = Utility::split(line);
    // ...
SkipAndRestart:

You could用过的words之后SkipAndRestart:标签，这本来就是一个问题。你在你的例子中没有使用它，但是words变量不会被破坏，直到end因此，对于编译器而言，该变量在标签处仍在使用中。

您可以通过放置来避免这种情况words在自己的范围内：

    if(line.size() < 2)
        goto SkipAndRestart;
    {
        std::vector<std::string> words = Utility::split(line);
        // ...
    }
SkipAndRestart:

请注意，continue语句跳转到循环的末尾，此时您实际上can't贴上标签。这是循环内任何局部变量被销毁之后、跳回到循环顶部之前的点。