typedef struct and enum, why?

Question

Possible Duplicates:
Purpose of struct, typedef struct, in C++
typedef struct vs struct definitions

In code that I am maintaining I often see the following:

typedef enum { blah, blah } Foo;
typedef struct { blah blah } Bar;

Instead of:

enum Foo { blah, blah };
struct Bar { blah blah };

I always use the latter, and this is the first time I am seeing the former. So the question is why would one use one style over the other. Any benefits? Also are they functionally identical? I believe they are but am not 100% sure.

score 10 · Accepted Answer · answered Feb 28 '11 at 21:01

10

In C++ this doesn't matter.

In C, structs, enums, and unions were in a different "namespace", meaning that their names could conflict with variable names. If you say

struct S { };

So you could say something like

struct S S;

and that would mean that struct S is the data type, and S is the variable name. You couldn't say

S myStruct;

in C if S was a struct (and not a type name), so people just used typedef to avoid saying struct all the time.

answered Feb 28 '11 at 21:01

user541686

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`enum`, `union`, and `struct` have the same issue. – user541686 Feb 28 '11 at 21:06
Yea, I re-read your answer and realized that and then deleted my comment. Oops. Thanks! – anio Feb 28 '11 at 21:08
@anio: Haha okay, no problem. – user541686 Feb 28 '11 at 21:08

score 3 · Answer 2 · answered Feb 28 '11 at 21:01

3

They are for C compatability. A normal

  struct Bar { blah, blah };

doesn't work the same with C;

answered Feb 28 '11 at 21:01

Nick Banks

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typedef struct and enum, why?

2 Answers2