Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
894 views
in Technique[技术] by (71.8m points)

macros - Are typedef and #define the same in c?

I wonder if typedef and #define are the same in ?

Question&Answers:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

typedef obeys scoping rules just like variables, whereas define stays valid until the end of the compilation unit (or until a matching undef).

Also, some things can be done with typedef that cannot be done with define.
For example:

typedef int* int_p1;
int_p1 a, b, c;  // a, b, c are all int pointers

#define int_p2 int*
int_p2 a, b, c;  // only the first is a pointer, because int_p2
                 // is replaced with int*, producing: int* a, b, c
                 // which should be read as: int *a, b, c
typedef int a10[10];
a10 a, b, c;  // create three 10-int arrays
typedef int (*func_p) (int);
func_p fp;  // func_p is a pointer to a function that
            // takes an int and returns an int

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...