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使用realloc获得的扩展内存包含了什么？

[英]What are the contains of the extended memory obtained using realloc?

原文 2018-10-01 12:17:07 4 2 c/ realloc

When I use realloc to re-size the memory which I used calloc earlier to initialize (an array), is it still remains 0 in a whole buffer? 当我使用realloc来重新调整我之前使用calloc初始化（一个数组）的内存时，它是否仍然在整个缓冲区中保持为0？ or the new part is not initialized? 或新部分未初始化？

2 个解决方案

Considering you're increasing the size of the allocated memory, the extended memory region will have indeterminate values. 考虑到您增加了已分配内存的大小，扩展内存区域将具有不确定的值。

Quoting C11 , chapter §7.22.3.5, ( emphasis mine ) 引用C11 ，章节§7.22.3.5，（ 强调我的 ）

[...] The contents of the new object shall be the same as that of the old object prior to deallocation, up to the lesser of the new and old sizes. [...]新对象的内容应与解除分配之前的旧对象的内容相同，直到新旧大小中的较小者为止。 Any bytes in the new object beyond the size of the old object have indeterminate values. 新对象中超出旧对象大小的任何字节都具有不确定的值。

No, unfortunately realloc will not initialize the "new" part that is allocated. 不，遗憾的是realloc不会初始化分配的“新”部分。 So you have to do that yourself. 所以你必须自己做。 The "old" part will keep its value, though, so if you didn't change that, all your 0 s will still be there. 但是，“旧”部分将保留其价值，所以如果你没有改变它，你的所有0都将保持在那里。

使用realloc（）初始化内存 - Initializing the memory using realloc()

使用realloc并将内存写入新地址时会发生什么？ - What happens when using realloc and memory is written to a new address?

使用realloc填满内存 - filling up memory using realloc

C：通过使用realloc导致内存错误 - C: memory error by using realloc

使用realloc缩小内存分配 - Using realloc to shrink memory allocation

在clang中使用realloc来缩小内存 - Using realloc in clang to shrink memory

使用 realloc 收缩分配的 memory - Using realloc to shrink the allocated memory

如果没有连续的内存空间，realloc会怎么做？ - What would realloc do if there is no sequential space of memory?

使用realloc减少数组时内存会发生什么？ - What happens with the memory when decrease array with realloc?

C - 使用 malloc，重新分配和释放。我得到太多 memory 泄漏，怎么了？ - C - Using malloc, realloc and free. I get too many memory leaks, what's wrong?

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相关问题 使用realloc（）初始化内存 - Initializing the memory using realloc() 使用realloc并将内存写入新地址时会发生什么？ - What happens when using realloc and memory is written to a new address? 使用realloc填满内存 - filling up memory using realloc C：通过使用realloc导致内存错误 - C: memory error by using realloc 使用realloc缩小内存分配 - Using realloc to shrink memory allocation 在clang中使用realloc来缩小内存 - Using realloc in clang to shrink memory 使用 realloc 收缩分配的 memory - Using realloc to shrink the allocated memory 如果没有连续的内存空间，realloc会怎么做？ - What would realloc do if there is no sequential space of memory? 使用realloc减少数组时内存会发生什么？ - What happens with the memory when decrease array with realloc? C - 使用 malloc，重新分配和释放。我得到太多 memory 泄漏，怎么了？ - C - Using malloc, realloc and free. I get too many memory leaks, what's wrong?

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