在阅读内核碰到结构体的点号和冒号"."and":"

 C99(c语言标准)用点号。linux kernel 中的冒号是gcc的扩展。

.a表示结构体Str的成员，用来初始化。

当结构体里有很多成员的话，这样会方便和清晰很多 

int main() { Str s = { .a = 1, .b = 2};//注意这里的点 printf("a=%d/nb=%d/n",s.a,s.b); } typedef struct str{ int a; int b;}Str;int main(){ Str s={a:1,b:2};//注意这里的冒号 printf("a=%d/nb=%d/n",s.a,s.b);}

原文是在linux内核2.4.18的linux/fs/ext2/super.c文件里的，如下：
冒号的作用应该是和点号一样

   static struct super_operations ext2_sops = { read_inode: ext2_read_inode, write_inode: ext2_write_inode, put_inode: ext2_put_inode, delete_inode:ext2_delete_inode, put_super: ext2_put_super, write_super: ext2_write_super, statfs: ext2_statfs, remount_fs: ext2_remount,};

super_operations的定义在linux/include/linux/fs.h文件中，原文为：

struct super_operations { void (*read_inode) (struct inode *); /* reiserfs kludge. reiserfs needs 64 bits of information to ** find an inode. We are using the read_inode2 call to get ** that information. We don't like this, and are waiting on some ** VFS changes for the real solution. ** iget4 calls read_inode2, iff it is defined */ void (*read_inode2) (struct inode *, void *) ; void (*dirty_inode) (struct inode *); void (*write_inode) (struct inode *, int); void (*put_inode) (struct inode *); void (*delete_inode) (struct inode *); void (*put_super) (struct super_block *); void (*write_super) (struct super_block *); void (*write_super_lockfs) (struct super_block *); void (*unlockfs) (struct super_block *); int (*statfs) (struct super_block *, struct statfs *); int (*remount_fs) (struct super_block *, int *, char *); void (*clear_inode) (struct inode *); void (*umount_begin) (struct super_block *); /* Following are for knfsd to interact with "interesting" filesystems * Currently just reiserfs, but possibly FAT and others later * * fh_to_dentry is given a filehandle fragement with length, and a type flag * and must return a dentry for the referenced object or, if "parent" is * set, a dentry for the parent of the object. * If a dentry cannot be found, a "root" dentry should be created and * flaged as DCACHE_NFSD_DISCONNECTED. nfsd_iget is an example implementation. * * dentry_to_fh is given a dentry and must generate the filesys specific * part of the file handle. Available length is passed in *lenp and used * length should be returned therein. * If need_parent is set, then dentry_to_fh should encode sufficient information * to find the (current) parent. * dentry_to_fh should return a 1byte "type" which will be passed back in * the fhtype arguement to fh_to_dentry. Type of 0 is reserved. * If filesystem was exportable before the introduction of fh_to_dentry, * types 1 and 2 should be used is that same way as the generic code. * Type 255 means error. * * Lengths are in units of 4bytes, not bytes. */ struct dentry * (*fh_to_dentry)(struct super_block *sb, __u32 *fh, int len, int fhtype, int parent); int (*dentry_to_fh)(struct dentry *, __u32 *fh, int *lenp, int need_parent); int (*show_options)(struct seq_file *, struct vfsmount *);};