Thread: typedef

I sort of understand the typedef keyword like this.
typedef int count;
that will make count the same as int. so everytime the compiler sees count it replaces it with int right?
If that is right I also have a question about structures typedefing

Code:

struct info{
             int x;
             char name[10];
}
struct info mike;

now I know you can do this

Code:

typedef struct info{
           int x;
           char name[10];
}
info mike;

If what i said about earlier typedefs is right how does it get rid of the struct part. Thanx in advance.

Your code is quite weird, first, you forgot the ';' at the end of the struct block in both examples, besides, the second one isn't complete, it should be:

Code:

typedef struct info {
    int x;
    char name[10];
} info;
info mike;

About the way the compiler does, it is a little more complex, a typedef defines an equivalent in all points to a given type, not just a replacement.

example:

Code:

typedef int *intp;
intp p1, p2;  /* Here, both lpv and pv are int * */
int *pn, n;  /* Only pn is a int *, n is a simple int */

Code:

typedef struct info {
    int x;
    char name[10];
}info;

Hmmm ... I think this is invalid code. "info" two times ... that doesn't work.
This should be correct:

Code:

typedef struct {
    int x;
    char name[10];
} info;

info mike;

I was always successful using this kind of code, now, maybe isn't it standard but my compiler did never complain. Well, to me these are different labels, "struct info" and "info" itself. The rule is probably, try by yourself.
By the way, I usually use different tags but it seemed (to me...) that the code shown above (in the first post) was designed so that the same name could be used without the "struct" thing.

Originally posted by Dave_Sinkula
It is valid. The structure tag and the typedef are in separate identifier namespaces. Here is a better explanation.

You're right. Now it's quite obvious to me why the code is valid indeed. And thank you for the link.