C++/C macro Definition (define) # # # meaning Macro stitching

The Meaning of # # # in C++/C macro definition (define)

# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # define.

#是字符串化的意思, the # that appears in the macro definition is a string that is followed by a parameter;

eg

#define STRCPY__ (DST, SRC) strcpy (DST, #src)

Strcpy__ (BUFF,ABC) equivalent to strcpy__ (buff, "abc")

# #是连接符号, connect the parameters together

#define FUN (ARG) my# #arg

Then Fun (ABC)

Equivalent to MYABC

Let's look at a concrete example.

#include <iostream>

using namespace Std;

#define OUTPUT (a) cout<< #A << ":" << (a) <<endl;

int main () {

int a=1,b=2;

OUTPUT (a);

OUTPUT (b);

OUTPUT (A+B);

return 1; }

# # # # # # # # # # # # # # # # # # # # # # We get this result, we print the value of a, B, it's in accordance with the grammatical rules #include <iostream>

using namespace Std;

#define OUTPUT (a) cout<<a<< ":" << (a) <<endl;

int main ()

{

int a=1,b=2;

OUTPUT (a);

OUTPUT (b);

OUTPUT (A+B);

return 1;

}

C++/C macro Definition (define) # # # meaning Macro stitching