differences between struct and typedef struct

**stanlvw** · 07-22-2008

This may have been asked before and may also be trivial, but I'm curious between the differences of:

Code:

struct ANYTYPE
{
    // members
};

and:

Code:

typedef struct TYPENAME
{
      // members
} ANYTYPE;

Would be muchly appreciated to hear some thoughts.

**dwks** · 07-22-2008

When you name a structure with a tag like so,

Code:

struct tag {

};

you're declaring a structure tag that can be used together with the struct keyword to declare an instance of that structure.

Code:

struct tag instance;

When you use a typedef like this,

Code:

typedef struct {

} tag;

you're declaring a typedef by the name of tag which happens to map to a structure, and which you can use like this, without the "struct" keyword.

Code:

tag instance;

Basically, using typedef lets you leave off the struct keyword everywhere else.

(BTW, this is a C phenomenon. In C++, you can declare an instance of a struct or a class with just the tag name, with no typedef required.)

Thread: differences between struct and typedef struct