blocks|key|2810921|text|因为array是全局的，所以它对其他函数是可见的。在被delete[]释放之前，使用new[]分配的内存会一直存在。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2810922|entityMap^0|2|5|R|8|16|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

Since <code>array</code> is global, it is visible to other functions. Memory allocated with <code>new[]</code> stays around until it is freed by <code>delete[]</code>.

blocks|key|4883065|text|它将存在并且是全局的，因为char+*+array指针是全局的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4883066|entityMap^0|D|C|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

It will exist and be global, because the <code>char * array</code> pointer is global.

blocks|key|1195390|text|首先，它当然会存在于外部，这就是动态分配的全部内容。此外，变量本身是全局的。此外，它应该是一个char+const**+array;，并且分配应该是new+char+const*[3]+(注意方括号)。const，因为您不会在这里更改字符串的内容。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1195391|其次，，不会这么做。只需将其放在一个类中并使用std::vector即可！|BOLD|1195392|#include+<vector>

class+Foo{
public:
++function_1(){
++++_array.push_back("value+1");
++++_array.push_back("value+2");
++++_array.push_back("value+3");
++}

++function_2(){
++++_array[0]+=+("new+value+1");
++}

private:
++std::vector<std::string>+_array;
};

int+main(){
++Foo+f;
++f.function_1();
++f.function_2();
}|code-block|syntax|javascript|1195393|更好的是，拥有一个std::vector<std::string>，这样您就可以安全地修改内容，而不必担心内存管理。尽管如此，这将不再是一个单独的块。现在我要问的是，您到底想如何将缓冲区传递给套接字？|1195394|entityMap^0|1B|J|22|I|2T|5|0|4|X|N|B|0|0|0|2S|9|O|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@$9|Z|A|10|B|H]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|I|3|J|5|K|7|13|8|@]|D|@]|E|$L|M]]|$1|N|3|O|5|6|7|14|8|@$9|15|A|16|B|H]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|P|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|Q|$]]

First, of course it will exist outside, that's all what dynamic allocation is about. Also, the variable itself is global. Also, it should be a <code>char const** array;</code> and the allocation should be <code>new char const*[3]</code> (note the square brackets). The <code>const</code> because you won't change the contents of the strings here.

Second, don't do that. Just put it in a class and use a <code>std::vector</code>!

<pre><code>#include &lt;vector&gt;

class Foo{
public:
 function_1(){
 _array.push_back("value 1");
 _array.push_back("value 2");
 _array.push_back("value 3");
 }

 function_2(){
 _array[0] = ("new value 1");
 }

private:
 std::vector&lt;std::string&gt; _array;
};

int main(){
 Foo f;
 f.function_1();
 f.function_2();
}
</code></pre>

Even better, have a <code>std::vector&lt;std::string&gt;</code>, so you can safely modify the contents without having to worry about memory management. Though, to this won't be a single block any more. Now I got to ask, how exactly do you want to pass the buffer to the socket?

blocks|key|2811014|text|您在function1中分配的内存将在程序退出函数的作用域后保持分配状态，并将在函数2和3中正常工作。但是，请注意，如果您在调用函数1之前调用函数2和3，则该行为是未定义的。一般来说，您在这里尝试做的事情看起来像是糟糕的设计，但为了这个问题，我现在不会困扰您:)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2811015|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The memory that you allocate in function1 will stay allocated after the program exits the scope of the function and will work as expected in functions 2 and 3. Notice however, that behaviour is undefined if you call functions 2 and 3 before function one. In general though, what you're trying to do here looks like bad design, but for the sake of the question I won't bug you about that now :)

blocks|key|4883141|text|实际上，您的function_1()中有一个致命错误。下面的代码将导致array指向一个值为3的字符，然后它将覆盖相邻内存的各个部分，基本上导致缓冲区溢出。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4883142|void+function_1()+{
++++array+=+new+char(3);
++++array[0]+=+"value+1";
++++array[1]+=+"value+2";
++++array[2]+=+"value+3";
}|code-block|syntax|javascript|4883143|你可能想做的是创建类似这样的东西：|4883144|char+**array;
array+=+new+char*[3];
array[0]+=+new+char[strlen(...)];
array[0]+=+strncpy(array[0],+...,+strlen(...)];
//+etc|4883145|实现这一点的一种更安全、更简洁的方法是按照Xeo的建议，使用std::vector而不是普通数组。|4883146|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You actually have a fatal error in your function_1(). The following code will cause array to point to a character, with the value 3. Then, it will overwrite various parts of neighboring memory, basically causing a buffer overflow.

<pre><code>void function_1() {
 array = new char(3);
 array[0] = "value 1";
 array[1] = "value 2";
 array[2] = "value 3";
}
</code></pre>

What you probably want to do is create something like:

<pre><code>char **array;
array = new char*[3];
array[0] = new char[strlen(...)];
array[0] = strncpy(array[0], ..., strlen(...)];
// etc
</code></pre>

A much safer and cleaner way of accomplishing this would be to do what Xeo is suggesting, and using a std::vector instead of a plain array.

blocks|key|2811052|text|如果你能做到以下几点，你会大大提高代码的清晰度：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2811053|2811054|使用std::+vector，特别是如果您打算稍后调整它的大小|unordered-list-item|2811055|使用std::string表示字符串|2811056|通过引用需要它的函数传递数组或向量。|2811057|2811058|int+main()+{+std::vector+vect；function_1(vect)；function_2(vect)；}|2811059|您的函数如下所示：|2811060|void+function_1(std::vector<std::string>+&+Vect)+|code-block|syntax|javascript|2811061|typedefs帮助管理参数类型|offset|length|style|CODE|2811062|这样你就不必担心泄露了，因为向量在超出范围时会自动释放。|2811063|entityMap^0|0|0|0|0|0|0|0|0|0|0|8|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|14|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|15|8|@]|9|@]|A|$]]|$1|F|3|G|5|E|7|16|8|@]|9|@]|A|$]]|$1|H|3|I|5|E|7|17|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|18|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|19|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|1B|8|@]|9|@]|A|$R|S]]|$1|T|3|U|5|6|7|1C|8|@$V|1D|W|1E|X|Y]]|9|@]|A|$]]|$1|Z|3|10|5|6|7|1F|8|@]|9|@]|A|$]]|$1|11|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|12|$]]

It would greatly improve the clarity of your code if you'd:

<ul>
<li>use a std::vector, especially if you plan to resize it later</li>
<li>use a std::string to represent strings</li>
<li>pass the array or vector by reference to the functions that need it.

<pre><code>int main() {
std::vector&lt;std::string&gt; vect;

function_1(vect);
function_2(vect);
}
</code></pre></li>
</ul>

where your functions look like:

<pre><code>void function_1(std::vector&lt;std::string&gt; &amp; Vect) 
</code></pre>

<code>typedefs</code> help manage the argument types

This way you won't have to worry about leaks as the vector will deallocate itself when out of scope.

I am writing a programm in C++. In my programm I need to create an array with dynamic size inside one function, but this array should be also accessable for other functions. I will not post here my code, just write one dummy example.

<pre><code>char *array;


void function_1() {
 array = new char(3);
 array[0] = "value 1";
 array[1] = "value 2";
 array[2] = "value 3";
}

void function_2() {
 array[0] = "new value 1";
}

int main() {
 function_1();
 function_2();

 delete[] array;
}
</code></pre>

My question is: I am not sure, if the array will exist outside the function_1, where it was initialised, until I delocate a memory of array.
Or the array will have just a behaviour of local variable inside one function. What means, that the memory, which stores the array values, will be dellocated after the function is finished and the memory addresses of my array can be rewroten with something else later in my programm.

Thank you.

create global dynamic array inside the function

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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我正在用C++写一个程序。在我的程序中，我需要在一个函数中创建一个动态大小的数组，但这个数组也应该可以被其他函数访问。我不会在这里发布我的代码，只写一个虚构的例子。char *array;void function_1() {    array = new char(3);    array[0] = "value 1...

问在函数内部创建全局动态数组
EN

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问在函数内部创建全局动态数组EN