Why char name[0]? [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicate:

zero length arrays

Recently, I've been reading the FUSE source code and the dirent struct is defined as follows:

struct fuse_dirent
{
    __u64 ino;
    __u64 off;
    __u32 namelen;
   开发者_运维知识库 __u32 type;
    char name[0];
}

Can anyone explain what name[0] means here? What is it for? For padding and alignment?

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I've seen this "pattern" in Microsoft's code, usually when the struct in object's size is not known a priori.

You don't allocate it with the usual way, but you do something like:

struct fuse_dirent* data = malloc(sizeof(fuse_dirent) + ... );

then you can access the extra data by accessing name member.

Of course, this practice is not safe, so you have to pay extra attention.

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When this structure is allocated, some additional space will also be allocated at the end for storing a string. This way, the string can be accessed through fuse_dirent::name as if it were a "real" char * type. The reason for it being [0] is to not allocate any additional space in the fuse_direct "header".

An example:

fuse_dirent *d = malloc(sizeof(fuse_dirent) + 3);
strcpy(d->name, "hi");
printf(d->name); // will print "hi" to the console