Syntax Question

[aurelien.chanudet]

Hi all,

Can someone tell me about the difference between these two statements ?

char *string = _("foo");
char *string = "foo";

Thanks,
Aurelien

 

[Richard Heathfield]

(e-mail address removed) said:

Hi all,

Can someone tell me about the difference between these two statements ?

char *string = _("foo");

This is a function call to a function named _ which appears to accept a
const char * (or, lamely, a char *) and return a pointer to char. What
value it returns is anyone's guess. Alternatively, _ might be a macro.

char *string = "foo";

This is a definition and initialisation of a pointer to char. Its initial
value is the address of the first character in the string literal, "foo". A
better definition would be:

const char *string = "foo";

as you wouldn't want accidentally to modify the contents of a string literal
through a pointer, now would you?

 

[aurelien.chanudet]

I didn't know "_" was legal as a function or macro name. Thanks !

 

[Jaspreet]

I didn't know "_" was legal as a function or macro name. Thanks !

Identifiers beginning with _ (underscore) are valid in some
implementations but may raise a error flag on other. So to make your
program a portable solution, its ideal to not have an identifier name
starting with _.

But then we do not live in an ideal world.

 

[Jordan Abel]

Identifiers beginning with _ (underscore) are valid in some
implementations but may raise a error flag on other.

Not quite. they're 'reserved', so using them causes undefined behavior.
There is also a distinction between A) identifiers beginning with an
underscore and an uppercase letter (these are reserved everywhere) and
B) identifiers beginning with an underscore and a lowercase letter, an
underscore and a digit, or the identifier consisting of an underscore
alone (these are only reserved in some contexts, and not others)

 

[Ben Pfaff]

(e-mail address removed) said:


This is a function call to a function named _ which appears to accept a
const char * (or, lamely, a char *) and return a pointer to char. What
value it returns is anyone's guess. Alternatively, _ might be a macro.

My guess is that _ is a macro that expands to gettext, because
that's a common convention in Unix code. In turn,
gettext("Hello!") might return "Bonjour!"; in other words, it's
used for internationalization.

 

[Martin Ambuhl]

Hi all,

Can someone tell me about the difference between these two statements ?

char *string = _("foo");
char *string = "foo";

The first has no meaning without more context. Most likely, _() is a
macro the definition of which you have decided not to show us, for your
own secret reasons.