malloc()和calloc() [英] malloc() and calloc()

问题描述

有人可以帮我吗?

malloc()和calloc()有什么区别?

Hi, Can any one help me.

what is the difference between malloc() and calloc()?
Explain in deep manner.

推荐答案

malloc是内存分配的主力军(calloc本身使用malloc).
只需查看以下MSDN页，您可能会发现自己两个函数之间的区别:
malloc [ calloc [ ^ ].
:)

malloc is the workhorse for memory allocation (calloc itself uses malloc).
You may find yourself the differences between the two functions just having a look at the following MSDN pages:
malloc[^], calloc[^].
:)

calloc提供的已分配内存初始化为零，而malloc分配的内存仅包含其之前的所有垃圾.

同样，calloc接受2个参数，一个用于对象数，一个用于对象的大小，而malloc仅接受要分配的字节数.我相信calloc分配的内存可能会比预期的稍大，因为对象可以与任何相关的平台边界对齐.目的是在将项作为数组访问时使用calloc.

希望有帮助，
Charles Keepax

The allocated memory supplied by calloc is zero initialised, whereas that allocated by malloc just contains whatever junk was in their before.

Also calloc takes 2 arguments one for the number of objects and one for the size of an object, whereas malloc takes just the number of bytes to be allocated. I believe memory allocated by calloc can be slightly larger than expected as the objects can be aligned to any relevant platform boundaries. The intention is for calloc to be used if items are to accessed as an array.

Hope that helps,
Charles Keepax

函数void* malloc(size_t size)用于分配size 个字节.
它返回一个指向已分配块的指针.

函数void* calloc(size_t nelement, size_t elementSize)分配了足够的内存来存储总共大小为elementSize的nelement个元素.您可以使用它来分配已知数量的元素，例如分配10个my_struct s:

The function void* malloc(size_t size) is used to allocate size number of bytes.
It returns a pointer to the allocated block.

The function void* calloc(size_t nelement, size_t elementSize) allocates enough memory to store a total of nelement elements of size elementSize. You''d use this to allocate a known number of elements, such as allocating 10 my_structs:

struct my_struct
{
    int x;
    int y;
}

...

my_struct* = calloc(10, sizeof(my_struct);

此处 [

It''s explained in more detail here[^]

The memory is also initialized when using calloc.

Hope this helps,
Fredrik

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