blocks|key|1217856|text|我假设您使用的是C99编译器(支持动态调整数组大小)。您代码中的问题是，当编译器看到您的变量声明时，它无法知道数组中有多少个元素(我在这里也假设，从编译器错误中可以看出，length不是一个编译时间常数)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1217857|您必须手动初始化该数组：|1217858|int+boardAux[length][length];
memset(+boardAux,+0,+length*length*sizeof(int)+);|code-block|syntax|javascript|1217859|entityMap^0|2D|6|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

I am assuming that you are using a C99 compiler (with support for dynamically sized arrays). The problem in your code is that at the time when the compilers sees your variable declaration it cannot know how many elements there are in the array (I am also assuming here, from the compiler error that <code>length</code> is not a compile time constant). 

You must manually initialize that array:

<pre><code>int boardAux[length][length];
memset( boardAux, 0, length*length*sizeof(int) );
</code></pre>

blocks|key|1003590|text|这将产生错误：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1003591|int+len;
scanf("%25d",&len);
char+str[len]="";|code-block|syntax|javascript|1003592|这也会产生错误：|1003593|int+len=5;
char+str[len]="";|1003594|但这很好用：|1003595|int+len=5;
char+str[len];+//so+the+problem+lies+with+assignment+not+declaration|1003596|您需要用以下方式来赋值：|1003597|str[0]='a';
str[1]='b';+//like+that;+and+not+like+str="ab";|1003598|entityMap^0|0|0|0|0|0|0|0|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]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

This gives error: 

<pre><code>int len;
scanf("%d",&amp;len);
char str[len]="";
</code></pre>

This also gives error:

<pre><code>int len=5;
char str[len]="";
</code></pre>

But this works fine:

<pre><code>int len=5;
char str[len]; //so the problem lies with assignment not declaration
</code></pre>

You need to put value in the following way:

<pre><code>str[0]='a';
str[1]='b'; //like that; and not like str="ab";
</code></pre>

blocks|key|1217975|text|在声明数组之后|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1217976|int+boardAux[length][length];|code-block|syntax|javascript|1217977|将初始值赋值为零的最简单方法是使用for循环，即使它可能有点长|1217978|int+i,+j;
for+(i+=+0;+i<length;+i%2B%2B)
{
++++for+(j+=+0;+j<length;+j%2B%2B)
++++++++boardAux[i][j]+=+0;
}|1217979|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

After declaring the array

<pre><code>int boardAux[length][length];
</code></pre>

the simplest way to assign the initial values as zero is using for loop, even if it may be a bit lengthy

<pre><code>int i, j;
for (i = 0; i&lt;length; i++)
{
 for (j = 0; j&lt;length; j++)
 boardAux[i][j] = 0;
}
</code></pre>

blocks|key|1003872|text|可变长度数组是编译器在编译时不知道其长度的数组。在本例中，length是一个变量。我得出这个结论，因为如果length是一个预处理器宏，例如定义为文字整数，那么您的初始化将会起作用。1989年的第一个C语言标准不允许可变长度数组，它们是在1999年添加的。尽管如此，C标准仍然不允许用您的表达式来初始化它们(尽管有人可能会争辩说它可以或应该允许这样做)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1003873|初始化变量数组的最佳方法如下：|1003874|int+boardAux[length][length];
memset(+boardAux,+0,+sizeof(boardAux)+);|code-block|syntax|javascript|1003875|memset是一个非常快速的标准库函数，用于初始化内存(在上面的例子中初始化为0)。sizeof(boardAux)返回boardAux占用的字节数。sizeof始终可用，但memset需要#include+<string.h>。是的-+sizeof允许一个可变大小的对象作为参数。|1003876|注意，如果你有一个普通的数组(不是可变长度的)，并且只想将内存初始化为零，你永远不需要嵌套的括号，你可以像这样简单地初始化它：|1003877|struct+whatEver+name[13][25]+=+{0};|1003878|entityMap^0|T|6|1H|6|0|0|0|0|6|16|G|1O|8|23|6|2F|6|2N|J|3B|6|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]|$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|O|3|P|5|6|7|1G|8|@]|D|@]|E|$]]|$1|Q|3|R|5|J|7|1H|8|@]|D|@]|E|$K|L]]|$1|S|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]]|T|$]]

Variable length arrays are arrays whose length is not known by the compiler at compile time. In your case <code>length</code> is a variable. I conclude this, because if <code>length</code> was a e.g. preprocessor macro defined as a literal integer your initialization would work. The first C language standard from 1989 did not allow variable length arrays, they were added in 1999. Still the C standard does not allow these to be initialized with an expression like yours (although one could argue that it could or should allow it).
The best way to initialize a variable array is like this:
<pre><code>int boardAux[length][length];
memset( boardAux, 0, sizeof(boardAux) );
</code></pre>
<code>memset</code> is a very fast standard library function for initializing memory (to 0 in the above case). <code>sizeof(boardAux)</code> returns the number of bytes occupied by <code>boardAux</code>. <code>sizeof</code> is always available but <code>memset</code> requires <code>#include &lt;string.h&gt;</code>. And yes - <code>sizeof</code> allows a variable sized object as argument.
Note that if you have a normal array (not variable length) and just want to initialize the memory to zero you never need nested brackets, you can initialize it simply like this:
<pre><code>struct whatEver name[13][25] = {0};
</code></pre>

blocks|key|1003776|text|这个问题已经得到了回答，但我想指出另一个解决方案，该方案速度快，如果长度不打算在运行时更改，则可以工作。在main()之前使用macro+#define来定义长度，在main()中，您的初始化将起作用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1003777|#define+length+10

int+main()
{
++++int+boardAux[length][length]+=+{{0}};
}|code-block|syntax|javascript|1003778|宏在实际编译之前运行，长度将是编译时常量(正如David+Rodríguez在他的回答中所提到的那样)。它实际上会在编译前将长度替换为10。|1003779|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The question is already answered but I wanted to point out another solution which is fast and works if length is not meant to be changed at run-time. Use macro #define before main() to define length and in main() your initialization will work:

<pre><code>#define length 10

int main()
{
 int boardAux[length][length] = {{0}};
}
</code></pre>

Macros are run before the actual compilation and length will be a compile-time constant (as referred by David Rodríguez in his answer). It will actually substitute length with 10 before compilation.

blocks|key|1218109|text|数组不是用指定的内存初始化的，并且抛出错误variable+sized+array+may+not+be+initialised我更喜欢通常的初始化方式，|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1218110|for+(i+=+0;+i+<+bins;+i%2B%2B)
++++++++arr[i]+=+0;|code-block|syntax|javascript|1218111|entityMap^0|L|17|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

The array is not initialized with the memory specified anf throws an error
<code>variable sized array may not be initialised</code>
I prefer usual way of initialization,
<pre><code>for (i = 0; i &lt; bins; i++)
 arr[i] = 0;
</code></pre>

blocks|key|1217925|text|只需将length声明为cons，如果不是，则应该动态分配内存|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1217926|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|$]]

Simply declare length to be a cons, if it is not then you should be allocating memory dynamically

blocks|key|1218066|text|int+size=5;
int+ar[size+]={O};

/*+This++operation+gives+an+error+-++
variable+sized+array+may+not+be+
initialised.++Then+just+try+this.+
*/
int+size=5,i;
int+ar[size];
for(i=0;i<size;i%2B%2B)
{
++++ar[i]=0;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1218067|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>int size=5;
int ar[size ]={O};

/* This operation gives an error - 
variable sized array may not be 
initialised. Then just try this. 
*/
int size=5,i;
int ar[size];
for(i=0;i&lt;size;i++)
{
 ar[i]=0;
}
</code></pre>

Why do I receive the error "Variable-sized object may not be initialized" with the following code? 

<pre><code>int boardAux[length][length] = {{0}};
</code></pre>

C compile error: "Variable-sized object may not be initialized"

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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为什么我收到以下代码的“可变大小的对象可能无法初始化”的错误？int boardAux[length][length] = {{0}};

问C编译错误：“可变大小的对象可能无法初始化”
EN

回答 8

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问C编译错误：“可变大小的对象可能无法初始化”
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