Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a
solution if one exists.
--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cyberspace.org | don't, I need to know. Flames welcome. 15 1292
Christopher Benson-Manica wrote On 12/13/05 12:39,: Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a solution if one exists.
#define TEST(type,list) type array[] = { list }
This seems pretty straightforward -- have I somehow
misread your question?
-- Er*********@sun.com
Eric Sosman wrote: Christopher Benson-Manica wrote On 12/13/05 12:39,: Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a solution if one exists.
#define TEST(type,list) type array[] = { list }
This seems pretty straightforward -- have I somehow misread your question?
-- Er*********@sun.com
What about the parenthesis? I think he is trying to avoid C99 varargs
macros.
-David
David Resnick <ln********@gmail.com> wrote: What about the parenthesis? I think he is trying to avoid C99 varargs macros.
Yes, I am. I am dealing with a C++ implementation that does not
support the C99 varargs macros (among other things).
--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cyberspace.org | don't, I need to know. Flames welcome.
David Resnick wrote On 12/13/05 13:14,: Eric Sosman wrote:
Christopher Benson-Manica wrote On 12/13/05 12:39,:
Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a solution if one exists.
#define TEST(type,list) type array[] = { list }
This seems pretty straightforward -- have I somehow misread your question?
What about the parenthesis? I think he is trying to avoid C99 varargs macros.
Aha: I *did* misread the question! Thanks, D R,
and sorry, C B-M.
-- Er*********@sun.com
Christopher Benson-Manica a écrit : Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a solution if one exists.
The obvious way :
#define TEST(T, a, b, c)\
T array[] = {a, b, c}
int main(void)
{
TEST (int, 1, 2, 3);
return 0;
}
But I guess you want a variable list. Il suggest this :
#include <stdio.h>
int main(void)
{
int array[] =
{
#define ITEM(value)\
value,
#include "test.itm"
#undef ITEM
};
size_t i;
for (i = 0; i < sizeof array / sizeof *array; i++)
{
printf ("array[%u] = %d\n", (unsigned) i, array[i]);
}
return 0;
}
with:
/* test.itm */
ITEM (12)
ITEM (34)
ITEM (56)
which is a trick I got here on c.l.c a few years ago. I'm using it day
and night to automate code generation ! Very powerful ! (Prefcet to give
a string to an enum, for example...)
--
A+
Emmanuel Delahaye
Eric Sosman a écrit : Christopher Benson-Manica wrote On 12/13/05 12:39,:
Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 }; #define TEST(type,list) type array[] = { list }
This seems pretty straightforward -- have I somehow misread your question?
AFAICT, it doesn't work as expected:
#include <stdio.h>
#define TEST(type, list) type array[] = { list }
int main(void)
{
TEST( int, (1,2,3) );
size_t i;
for (i = 0; i < sizeof array / sizeof *array; i++)
{
printf ("array[%u] = %d\n", (unsigned) i, array[i]);
}
return 0;
}
produces
array[0] = 3
Some comma operator trick, I guess...
--
A+
Emmanuel Delahaye
Christopher Benson-Manica wrote: Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a solution if one exists.
No, there isn't. The closest thing you can do is something like the
following which is quite ugly:
#define TEST(x,y) x array[]={y}
#define SEP ,
TEST(int, 1 SEP 2 SEP 3);
and I am not positive that even this is valid in C89.
Robert Gamble
Christopher Benson-Manica a écrit : Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a solution if one exists.
The obvious way :
#define TEST(T, a, b, c)\
T array[] = {a, b, c}
int main(void)
{
TEST (int, 1, 2, 3);
return 0;
}
But I guess you want a variable list. Il suggest this :
#include <stdio.h>
int main(void)
{
int array[] =
{
#define ITEM(value)\
value,
#include "test.itm"
#undef ITEM
};
size_t i;
for (i = 0; i < sizeof array / sizeof *array; i++)
{
printf ("array[%u] = %d\n", (unsigned) i, array[i]);
}
return 0;
}
with:
/* test.itm */
ITEM (12)
ITEM (34)
ITEM (56)
which is a trick I got here on c.l.c a few years ago. I'm using it day
and night to automate code generation ! Very powerful ! (Perfect to give
a string to an enum, for example...)
--
A+
Emmanuel Delahaye
Christopher Benson-Manica wrote: Is it possible to write a macro (in unextended C89) such that
TEST( int, (1,2,3) );
expands to
int array[]={ 1,2,3 };
? I strongly suspect that it is not, but I don't wish to overlook a solution if one exists.
-- Christopher Benson-Manica | I *should* know what I'm talking about - if I ataru(at)cyberspace.org | don't, I need to know. Flames welcome.
I assume you reject the (clunky)
#define TEST_1(type,val1) type array[]={val1}
#define TEST_2(type,val1,val2) type array[]={val1,val2}
....
-David
David Resnick <ln********@gmail.com> wrote: I assume you reject the (clunky)
#define TEST_1(type,val1) type array[]={val1} #define TEST_2(type,val1,val2) type array[]={val1,val2}
Yes :-)
--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cyberspace.org | don't, I need to know. Flames welcome.
Emmanuel Delahaye <em***@yourbranoos.fr> wrote: But I guess you want a variable list. Il suggest this :
(snip interesting technique)
which is a trick I got here on c.l.c a few years ago. I'm using it day and night to automate code generation ! Very powerful ! (Perfect to give a string to an enum, for example...)
That does look like a creative technique, and I'll look for
opportunities to use it. Unfortunately, it doesn't handle the actual
situation I hav; I admit that what I want to do is not a stupendous
idea. The ultimate idea was to allow use of "array literals" (such as
are found in JavaScript) to allow for macros like
if( TEST(int,1,(1,2,3)) ) { /* Checks for second argument in third */
/* ... */
}
None of the other options (inline function, C++ templates, etc.) are
particularly appetizing here either, so it seems that there is no
trick to avoiding tried-and-true (but boring) methods.
--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cyberspace.org | don't, I need to know. Flames welcome.
Robert Gamble <rg*******@gmail.com> wrote: #define TEST(x,y) x array[]={y} #define SEP , TEST(int, 1 SEP 2 SEP 3);
and I am not positive that even this is valid in C89.
It seems to work on my implementation, FWIW, but I concur that it is
probably too ugly to consider.
--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cyberspace.org | don't, I need to know. Flames welcome.
Christopher Benson-Manica <at***@nospam.cyberspace.org> writes: That does look like a creative technique, and I'll look for opportunities to use it. Unfortunately, it doesn't handle the actual situation I hav; I admit that what I want to do is not a stupendous idea. The ultimate idea was to allow use of "array literals" (such as are found in JavaScript) to allow for macros like
if( TEST(int,1,(1,2,3)) ) { /* Checks for second argument in third */ /* ... */ }
For small ranges, you can do something like this:
#define BIT(x) (1ul << (x))
#define BITS(x, y) (BIT(x) | (y))
if (BIT(x) & BITS(1, BITS(2, BIT(3))))
Not ideal.
--
"For those who want to translate C to Pascal, it may be that a lobotomy
serves your needs better." --M. Ambuhl
"Here are the steps to create a C-to-Turbo-Pascal translator..." --H. Schildt
On 2005-12-13, Christopher Benson-Manica <at***@nospam.cyberspace.org> wrote: David Resnick <ln********@gmail.com> wrote:
I assume you reject the (clunky)
#define TEST_1(type,val1) type array[]={val1} #define TEST_2(type,val1,val2) type array[]={val1,val2}
Yes :-)
how about (c99 only)
#define TEST(type,...) type array[] = { __VA_ARGS__ }
Jordan Abel wrote: On 2005-12-13, Christopher Benson-Manica <at***@nospam.cyberspace.org> wrote: David Resnick <ln********@gmail.com> wrote:
I assume you reject the (clunky)
#define TEST_1(type,val1) type array[]={val1} #define TEST_2(type,val1,val2) type array[]={val1,val2}
Yes :-)
how about (c99 only)
#define TEST(type,...) type array[] = { __VA_ARGS__ }
Apparently you missed the part about c99 not being an option, but yes,
this would be the obvious solution if it were.
Robert Gamble This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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