Question

我有这样的媒介:

std::vector<std::vector<char> > _lines;

我愿提醒这些病媒和病媒,然而,我不敢肯定我如何利用第一个病媒的主人接触内部病媒?

我已经做到以下几点:

std::vector<std::vector<char> >::iterator first_iter = _lines.begin();

        for (; first_iter != _lines.end(); first_iter++)
        {
            (*first_iter)::iterator second_iter = (*first_iter)->begin();  // something is wrong with this? How do I get the second vector to iterate?
        }

Answer 1

for (std::vector<std::vector<char> >::iterator i = _lines.begin();
                                               i != _lines.end(); ++i)
{
    for (std::vector<char>::iterator j = i->begin(); j != i->end(); ++j)
    {
        // ... use *j
    }
}

如果你使用现代汇编器,你可以使用C++0x特征auto,自动减少这种特性:

for (auto i = _lines.begin(); i != _lines.end(); ++i)
{
    for (auto j = i->begin(); j != i->end(); ++j)
    {
        // ... use *j
    }
}

Answer 2

您可具体说明如下类型:(*first_iter):iterator。 Just use std:vector<char>:iterator。

<代码>(*first_iter)->begin() [*first_iter.begin(<>code>(或first_iter->begin().*first_iter is a std:vector<char>, not a pointer.

Answer 3

您需要说明内部自动取款机的类型,因此不能通过经营人范围进入某类。

std::vector<char>::iterator second_iter = ...

Answer 4

std::vector<std::vector<char> >::iterator first_iter =_lines.begin();
for (; first_iter != _lines.end(); first_iter++) {

     std::vector<char>::iterator second_iter = (*first_iter).begin(); // or first_iter->begin()
     ...
}

Answer 5

这将是:

std::vector<std::vector<char> >::iterator first_iter = _lines.begin();

for (; first_iter != _lines.end(); first_iter++)
{
   std::vector<char>::iterator second_iter = first_iter->begin();
}

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