macros standard equivalent?

[aaragon]

Hello All,

I am using the following macros;

#define str(x) # x
#define conc(x,y) x ## y

to play with strings. Does anyone know if there is an equivalent
provided by the standard library to accomplish this? Thank you,

aa

 

[Victor Bazarov]

Hello All,

I am using the following macros;

#define str(x) # x
#define conc(x,y) x ## y

to play with strings. Does anyone know if there is an equivalent
provided by the standard library to accomplish this? Thank you,

No, there isn't anything. However, to properly concatenate those
you might want to use indirection, i.e. have another set of the two
macros to help:

#define applystringize(x) # x
#define str(x) applystringize(x)
#define applyconcatenate(x,y) x ## y
#define conc(x,y) applyconcatenate(x,y)

because otherwise if you use macros like 'conc(x, str(x))', it
won't do it without this extra indirection stuff.

V

 

[Phlip]

I am using the following macros;

#define str(x) # x
#define conc(x,y) x ## y

to play with strings. Does anyone know if there is an equivalent
provided by the standard library to accomplish this? Thank you,

Those are "stringerization" and "token pasting". They are one of a few
reasons to use macros, and nothing below the macro layer, in the layer of
C++ keywords, can do anything like them. They change the text that the see.
So

conc(in,t) x = 42;

gets compiled as

int x = 42;

Nothing in the standard library can ever do that!

(May we ask what you use those macros for? Situations that actually need
them are kind'a rare...)