blocks|key|577735|text|不，不可能在指针上使用std::begin和std::end。与数组不同的是，数组的大小是类型的一部分，因此，指针不包含它所指向的东西的大小。在这种情况下，您必须使用指针。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|577736|std::find(pStart,+pStart+%2B+SIZE,+5);|code-block|syntax|javascript|577737|但是，避免这种情况的方法是在编译时不知道szie将是什么时使用std::vector。它将为您管理内存，并提供begin和end成员函数。|577738|entityMap^0|B|A|M|8|0|0|V|B|1J|5|1P|3|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|N|$]]

No it is not possible to use <code>std::begin</code> and <code>std::end</code> on a pointer. Unlike an array whose size is part of the type and therefor deducible a pointer does not hold the size of the thing it points to. In your case with a pointer you would have to use

<pre><code>std::find(pStart, pStart + SIZE, 5);
</code></pre>

The way to avoid this though is to use <code>std::vector</code> when you are not going to know what the szie will be at compile time. It will manage the memory for you and provides <code>begin</code> and <code>end</code> member functions.

blocks|key|2726472|text|是否有可能让begin()和end()知道这一点？|type|blockquote|depth|inlineStyleRanges|entityRanges|data|2726473|可以为指针实现std::begin，但不可能实现std::end+(正如您所说的，大小未知)，因此它有点没有意义。|unstyled|offset|length|style|CODE|2726474|但是，您不需要任何一个都可以使用std::find|2726475|int*+p+=+std::find(pStart,+pStart+%2B+SIZE,+5);|code-block|syntax|javascript|2726476|entityMap^0|0|7|A|O|8|0|G|9|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|S|8|@$E|T|F|U|G|H]|$E|V|F|W|G|H]]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@$E|Y|F|Z|G|H]]|9|@]|A|$]]|$1|K|3|L|5|M|7|10|8|@]|9|@]|A|$N|O]]|$1|P|3|-4|5|D|7|11|8|@]|9|@]|A|$]]]|Q|$]]

<blockquote>
 Is it possible to make begin() and end() aware of it?
</blockquote>

It's possible to implement <code>std::begin</code> for a pointer, but it is impossible to implement <code>std::end</code> (because as you say, the size is unknown), so it is a bit pointless.

However, you don't need either of those to use <code>std::find</code>:

<pre><code>int* p = std::find(pStart, pStart + SIZE, 5);
</code></pre>

blocks|key|2246891|text|在此：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2246892|std::begin(pStart),+std::end(pStart)|code-block|syntax|javascript|2246893|你想取指针的开头和结尾。不是的！|2246894|相反，你的意思是：|2246895|std::begin(vect),+std::end(vect)|2246896|无论您使用数组、std::array、std::vector还是特别大的大象，这都是一样的--为了获得容器的边界，您需要容器。|offset|length|style|CODE|2246897|entityMap^0|0|0|0|0|0|8|A|J|B|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|Z|8|@$O|10|P|11|Q|R]|$O|12|P|13|Q|R]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|T|$]]

Here:

<pre><code>std::begin(pStart), std::end(pStart)
</code></pre>

you're trying to take the beginning and end of a pointer. Nope!

Instead, you meant:

<pre><code>std::begin(vect), std::end(vect)
</code></pre>

This is the same whether you use an array, or a <code>std::array</code>, or a <code>std::vector</code>, or a particularly large elephant &mdash; to get the bounds of a container, you need the container.

blocks|key|2726544|text|当我处理裸数组时，我依赖于简单的容器来使它们与C%2B%2B对范围的一般处理兼容。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2726545|例如：|2726546|#include+<iostream>
#include+<memory>++++//+for+std::unique_ptr
#include+<algorithm>+//+for+std::reverse
#include+<numeric>+++//+for+std::iota

template<typename+T>

class+range_view+{

+public:

++range_view(T*+data,+std::size_t+size)
++++++:+m_data+{+data+},
++++++++m_size+{+size+}+{+}

++const+T*+begin()+const+{+return+m_data;+}
++const+T*+end()+const+{+return+m_data+%2B+m_size;+}

++T*+begin()+{+return+m_data;+}
++T*+end()+{+return+m_data+%2B+m_size;+}

+private:

++T*+m_data;
++std::size_t+m_size;
};

int+main()+{

++//+this+is+your+actual+data
++auto+pdata+=+std::make_unique<int>(20);

++//+this+is+a+handle+you+use+to+work+with+your+data
++auto+data_view+=+range_view<int>(pdata.get(),+20);

++//+for+example,+you+can+fill+it+with+numbers+0,+...+,+N+-+1
++std::iota(data_view.begin(),+data_view.end(),+0);

++//+it+is+now+compatible+with+c%2B%2B's+range-based+operators
++std::cout+<<+"my+data...\n";
++for(auto+&&+item+:+data_view)+std::cout+<<+item+<<+"+";

++std::reverse(data_view.begin(),+data_view.end());
++std::cout+<<+"\nreversed...\n";
++for(auto+&&+item+:+data_view)+std::cout+<<+item+<<+"+";
++std::cout+<<+"\n";
}|code-block|syntax|javascript|2726547|编译和运行|2726548|$+g%2B%2B+example.cpp+-std=c%2B%2B14
$+./a.out
my+data...
0+1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+
reversed...
19+18+17+16+15+14+13+12+11+10+9+8+7+6+5+4+3+2+1+0+|2726549|您仍然需要担心将正确的维度传递给构造函数，如果删除了底层指针，它将不幸失败，但无论如何，您必须担心这一点。|2726550|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

When I deal with naked arrays I rely on simple containers to make them compatible with C++'s general treatment of ranges.

For example:

<pre><code>#include &lt;iostream&gt;
#include &lt;memory&gt; // for std::unique_ptr
#include &lt;algorithm&gt; // for std::reverse
#include &lt;numeric&gt; // for std::iota

template&lt;typename T&gt;

class range_view {

 public:

 range_view(T* data, std::size_t size)
 : m_data { data },
 m_size { size } { }

 const T* begin() const { return m_data; }
 const T* end() const { return m_data + m_size; }

 T* begin() { return m_data; }
 T* end() { return m_data + m_size; }

 private:

 T* m_data;
 std::size_t m_size;
};

int main() {

 // this is your actual data
 auto pdata = std::make_unique&lt;int&gt;(20);

 // this is a handle you use to work with your data
 auto data_view = range_view&lt;int&gt;(pdata.get(), 20);

 // for example, you can fill it with numbers 0, ... , N - 1
 std::iota(data_view.begin(), data_view.end(), 0);

 // it is now compatible with c++'s range-based operators
 std::cout &lt;&lt; "my data...\n";
 for(auto &amp;&amp; item : data_view) std::cout &lt;&lt; item &lt;&lt; " ";

 std::reverse(data_view.begin(), data_view.end());
 std::cout &lt;&lt; "\nreversed...\n";
 for(auto &amp;&amp; item : data_view) std::cout &lt;&lt; item &lt;&lt; " ";
 std::cout &lt;&lt; "\n";
}
</code></pre>

Compile and run

<pre><code>$ g++ example.cpp -std=c++14
$ ./a.out
my data...
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 
reversed...
19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 
</code></pre>

You still have to worry about passing the correct dimension to the constructor, and it will fail miserably if the underlying pointer is deleted, but you had to worry about that anyway.

blocks|key|2247004|text|我想对C%2B%2B数组使用迭代器，但也使用原始指针。|type|blockquote|depth|inlineStyleRanges|entityRanges|data|2247005|你倒过来了。原始指针是迭代器。它们在数组上迭代。|unstyled|offset|length|style|BOLD|2247006|您只需将它们用于您本来可以用std::begin和std::end完成的所有事情。最值得注意的是，您可以在C%2B%2B中将它们传递给<algorithm>标准算法。|CODE|2247007|指针本身不能迭代。迭代器不能迭代。|2247008|int*+pStart+=+vect；std：：find(std：：pStart(PStart)，std::end(pStart)，5)；|2247009|很松散地说，指针只是一个数字。数字的“开始”和“结束”是什么？这段代码几乎没有意义，如下所示：|2247010|int+i+=+123;
std::find(std::begin(i),+std::end(i),+5);+//+error|code-block|syntax|javascript|2247011|是否有可能让begin()和end()知道这一点？|2247012|指针可以指向某个数组的开头。但这些知识必须与指针保持一致。您需要保持一个大小或一个结束指针与一个开始指针，并保持所有的数据在一起。|2247013|这正是std::array和std::vector为你所做的。|2247014|entityMap^0|0|A|1|0|E|A|P|8|1R|B|0|0|0|0|0|6|7|E|5|0|0|3|A|E|B|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|15|8|@$E|16|F|17|G|H]]|9|@]|A|$]]|$1|I|3|J|5|D|7|18|8|@$E|19|F|1A|G|K]|$E|1B|F|1C|G|K]|$E|1D|F|1E|G|K]]|9|@]|A|$]]|$1|L|3|M|5|D|7|1F|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1G|8|@]|9|@]|A|$]]|$1|P|3|Q|5|D|7|1H|8|@]|9|@]|A|$]]|$1|R|3|S|5|T|7|1I|8|@]|9|@]|A|$U|V]]|$1|W|3|X|5|6|7|1J|8|@$E|1K|F|1L|G|K]|$E|1M|F|1N|G|K]]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1O|8|@]|9|@]|A|$]]|$1|10|3|11|5|D|7|1P|8|@$E|1Q|F|1R|G|K]|$E|1S|F|1T|G|K]]|9|@]|A|$]]|$1|12|3|-4|5|D|7|1U|8|@]|9|@]|A|$]]]|13|$]]

<blockquote>
 I want to use iterators with C++ arrays, but with raw pointers too.
</blockquote>

You got it backwards. Raw pointers are iterators. They iterate over arrays.

You can just use them for all the things you would otherwise accomplish with <code>std::begin</code> and <code>std::end</code>. Most notably, you can pass them to C++ standard algorithms in <code>&lt;algorithm&gt;</code>.

A pointer itself cannot be iterated. Iterators cannot be iterated.

<blockquote>
<pre><code>int* pStart = vect;
std::find(std::begin(pStart), std::end(pStart), 5);
</code></pre>
</blockquote>

Very loosely speaking, a pointer is just a number. What is the "begin" and "end" of a number? This piece of code makes as little sense as the following:

<pre><code>int i = 123;
std::find(std::begin(i), std::end(i), 5); // error
</code></pre>

<blockquote>
 Is it possible to make <code>begin()</code> and <code>end()</code> aware of it?
</blockquote>

A pointer may point to the beginning of some array. But that knowledge must be kept along with the pointer. You need to maintain a size or an end pointer along with a start pointer, and keep all that data together.

That's exactly what <code>std::array</code> and <code>std::vector</code> do for you.

blocks|key|2726557|text|虽然其他人的回答已经解释了为什么你应该重新审视你的设计，我想陈述一个选项，这不是前面描述的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2726558|您的编译器诊断消息几乎清楚地指出，编译器会推断参数，并且参数看起来与С样式数组的引用完全类似。|2726559|对C样式数组的引用不会衰减到指针，因此可以将对C样式数组的引用传递给std：：style和std::end+(在这种情况下)作为选项：|2726560|#include+<iostream>
#include+<algorithm>

constexpr+size_t+SIZE+=+10;

int+main()+{
++++int+vect[SIZE]+=+{0};
++++vect[3]+=+5;

++++int+(&ref_to_vect)[SIZE]+=+vect;++++//+declaring+reference+to+C-array

++++++++//+and+using+reference+to+C-array+which+doesn't+decay+to+pointer+opposite+to+passing+array+"by+value"+semantics
++++int*+p+=+std::find(std::begin(ref_to_vect),+std::end(ref_to_vect),+5);
++++bool+success+=+p+!=+std::end(vect);
++++std::cout+<<+(success+?+"Found+5"+:+"5+not+found+:(");

++++return+0;
}|code-block|syntax|javascript|2726561|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

While others answers already explains why you should revisit your design I want to state one option, that was not described earlier.
Your compiler diagnosis message almost clearly states that the compiler falls to deduce arguments and that arguments looks exactly like reference to С-style array.
Reference to C-style array doesn't decay to pointer, so you can pass reference to C-style array to std::begin and std::end in that particular case as an option:
<pre><code>#include &lt;iostream&gt;
#include &lt;algorithm&gt;

constexpr size_t SIZE = 10;

int main() {
 int vect[SIZE] = {0};
 vect[3] = 5;

 int (&amp;ref_to_vect)[SIZE] = vect; // declaring reference to C-array

 // and using reference to C-array which doesn't decay to pointer opposite to passing array &quot;by value&quot; semantics
 int* p = std::find(std::begin(ref_to_vect), std::end(ref_to_vect), 5);
 bool success = p != std::end(vect);
 std::cout &lt;&lt; (success ? &quot;Found 5&quot; : &quot;5 not found :(&quot;);

 return 0;
}
</code></pre>

I want to use iterators with C++ arrays, but with raw pointers too.
I can do with a static vector:

<pre><code>#define SIZE 10
int vect[SIZE] = {0};
vect[3] = 5;
int* p = std::find(std::begin(vect), std::end(vect), 5);
bool success = p != std::end(vect);
</code></pre>

How can be possible to do it with a raw pointer (maybe a heap allocated vector)?
Of course the compiler does not know the size of the data, so this code

<pre><code>int* pStart = vect;
std::find(std::begin(pStart), std::end(pStart), 5);
</code></pre>

gives

<pre><code>error C2784: '_Ty *std::begin(_Ty (&amp;)[_Size])' : 
could not deduce template argument for '_Ty (&amp;)[_Size]' from 'int *'
</code></pre>

Is it possible to make <code>begin()</code> and <code>end()</code> aware of it?

stl::iterators with raw pointers

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我想对C++数组使用迭代器，但也使用原始指针。我可以用一个静态向量：#define SIZE 10int vect[SIZE] = {0};vect[3] = 5;int* p = std::find(std::begin(vect), std::end(vect), 5);bool success = p != std::end(vect);如何能够使用原始指针(可能是堆分配的向量)来完成这个任

问stl：：带有原始指针的迭代器
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