c++ - String concatenation inside macro -

to print several fields of struct, have following line repeatedly:

cout << "field1=" << ptr->get_field1() 

so defined following macro, , use this:

#define field(s, id) << s"=" << ptr->get_##id()  field("field1", field1); field("field2", field2); 

this works. have mention same name twice in macro - once string, time variable. there better way it?

(the title of question not indicate question, not think of more appropriate short combination of words. sorry that!)

you should stringify id:

#define field(id) << #id "=" << ptr->get_##id()  field(field1);   // << "field1" "=" << ptr->get_field1() field(field2);   // << "field2" "=" << ptr->get_field2() 

live example

for field(field1), partly results in expression:

"field1" "=" 

which 2 literal strings put side-by-side. these 2 concatenated, resulting in string equivalent "field1=".