What's the correct syntax to define a function that returns a pointer to
a function? Specifically, I'd like a function that takes an int, and
returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint)
{
/* logic here */
}
but this doesn't seem to work.
:( 11 1944
Antoninus Twink wrote:
What's the correct syntax to define a function that returns a pointer to
a function? Specifically, I'd like a function that takes an int, and
returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint)
{
/* logic here */
}
but this doesn't seem to work.
:(
I have never managed to do it without a typedef...
char *fn1(int a)
{
return "function 1";
}
char *fn2(int a)
{
return "function 2";
}
typedef char *(*FunctionType )(int);
FunctionType FunctionReturni ngAFunctionPoin ter(int a)
{
if (a 0)
return fn1;
else
return fn2;
}
Antoninus Twink said:
What's the correct syntax to define a function that returns a pointer
to a function? Specifically, I'd like a function that takes an int,
and returns a pointer to a function that takes an int and returns a
string.
char *foo(int x)
{
static char bar[2];
bar[0] = x;
return bar;
}
char *(*baz(int n))(int)
{
/* use n in some way, I guess */
return foo;
}
--
Richard Heathfield <http://www.cpax.org.uk >
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999
Antoninus Twink wrote:
>
What's the correct syntax to define a function that returns a
pointer to a function? Specifically, I'd like a function that
takes an int, and returns a pointer to a function that takes an
int and returns a string.
I tried this:
gchar *(*f(gint n))(gint)
{
/* logic here */
}
but this doesn't seem to work.
:(
How about :
typedef char *stringfromint( int);
stringfromint *transfer(int) {
... amazing code ...
};
--
"Vista is finally secure from hacking. No one is going to 'hack'
the product activation and try and steal the o/s. Anyone smart
enough to do so is also smart enough not to want to bother."
--
Posted via a free Usenet account from http://www.teranews.com
Antoninus Twink <sp*****@invali d.comwrites:
What's the correct syntax to define a function that returns a pointer to
a function? Specifically, I'd like a function that takes an int, and
returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint)
{
/* logic here */
}
but this doesn't seem to work.
:(
Could the tool cundecl help you?
The function you have declared was right. I have a programme using it like
this:
#include <stdio.h>
char * (* func (int b)) (int); //The function returns a pointer.
char fun_1 (int a); //The function that the pointer pointed.
int main (void)
{
int b;
char ch;
char (*pre) (int a); //Declare an pointer point to func_1.
b = 98;
pre = (func (b)); //Get the pointer returned.
ch = (*pre) (b); //"pre" pointed to fun_1 ().
printf ( "ch = %c\n", ch);
return 0;
}
char func_1 (int a)
{
return a;
}
char * (* func (int b)) (int)
{
char (*pre) (int a);
if (b == 98)
pre = func_1;
return pre; //Return the pointer we want.
}
Exegesis: Visual C++ 6.0
"Antoninus Twink" <sp*****@invali d.comдÈëÏûϢРÎÅ:sl********** **********@nosp am.invalid...
What's the correct syntax to define a function that returns a pointer to
a function? Specifically, I'd like a function that takes an int, and
returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint)
{
/* logic here */
}
but this doesn't seem to work.
:(
Antoninus Twink wrote:
What's the correct syntax to define a function that returns a pointer to
a function? Specifically, I'd like a function that takes an int, and
returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint)
{
/* logic here */
}
but this doesn't seem to work.
:(
How about this?
#include <stdio.h>
typedef char*(*fp_t)(in t);
char glob[20];
char *foo(int i) {
sprintf(glob, "You've called foo with %d\n", i);
return glob;
}
char *bar(int i) {
sprintf(glob, "You've called bar with %d\n", i);
return glob;
}
fp_t baz(int i) {
fp_t ret;
if (i)
ret = foo;
else
ret = bar;
return ret;
}
int main(void) {
fp_t fun;
fun = baz(1);
puts(fun(42));
return 0;
}
--
Joe Wright
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---
On Sun, 5 Aug 2007 17:06:58 +0800, "Colonel" <xi**********@1 63.com>
wrote:
>The function you have declared was right. I have a programme using it like this:
#include <stdio.h>
If this is your actual code, you need to up the warning level of your
compiler and pay heed to the diagnostics.
>char * (* func (int b)) (int); //The function returns a pointer.
The pointer that func returns points to a function. That function
returns a char*.
>char fun_1 (int a); //The function that the pointer pointed.
fun_1 returns a char. Its address cannot be the return value from
func.
>int main (void) {
int b;
char ch;
char (*pre) (int a); //Declare an pointer point to func_1.
pre is a pointer to function that returns a char. It is compatible
with fun_1.
>
b = 98;
pre = (func (b)); //Get the pointer returned.
func returned a pointer to a function that returns a char*. It is
**not** compatible with pre.
ch = (*pre) (b); //"pre" pointed to fun_1 ().
printf ( "ch = %c\n", ch);
return 0; } char func_1 (int a) {
return a; } char * (* func (int b)) (int)
Again, the pointer that func returns points to a function returning a
char*. (This is compatible with the prototype above.)
>{
char (*pre) (int a);
Again, this local pre points to a function that returns char. It is
not compatible with the return type of func.
if (b == 98)
pre = func_1;
This is a constraint violation. The two operands of the assignment
operator are incompatible. There is no implicit conversion between
the two.
return pre; //Return the pointer we want.
It may be the pointer you want but it is the wrong type to return from
this function.
>}
Exegesis: Visual C++ 6.0 "Antoninus Twink" <sp*****@invali d.comдÈëÏûϢРÎÅ:sl********** **********@nosp am.invalid...
>What's the correct syntax to define a function that returns a pointer to a function? Specifically, I'd like a function that takes an int, and returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint) { /* logic here */ }
but this doesn't seem to work.
:(
Remove del for email
On Aug 4, 5:10 pm, Antoninus Twink <spam...@invali d.comwrote:
What's the correct syntax to define a function that returns a pointer to
a function? Specifically, I'd like a function that takes an int, and
returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint)
{
/* logic here */
}
but this doesn't seem to work.
:(
Define "doesn't seem to work." Are you getting a syntax error? A
runtime error? What?
f -- f
f() -- is a function
f(int n) -- that takes an integer
*f(int n) -- and returns a pointer
(*f(int n))() -- to a function
(*f(int n))(int m) -- that takes an integer
char *(*f(int n))(int m) -- and returns a char *
So, apart from the gint/gchar weirdness (I'm guessing this comes from
some API you're using), your definition looks all right to me.
char *foo(int m)
{
/* does something interesting */
}
char *bar(int m)
{
/* does something interesting */
}
char *bletch(int m)
{
/* does something interesting */
}
char *(*f(int n))(int m)
{
char *(*p)(int m);
switch(n)
{
case 0: p = foo; break;
case 1: p = bar; break;
case 2: p = bletch; break;
default: p = NULL; break;
}
return p;
}
int main(void)
{
char *result;
char *(*p)(int m);
int i;
for (i = 0; i < 4; i++)
{
p = f(i);
result = p(123);
if (result)
{
printf("result = %s\n", result);
}
}
return 0;
}
On Mon, 06 Aug 2007 14:45:01 -0700, John Bode wrote:
On Aug 4, 5:10 pm, Antoninus Twink <spam...@invali d.comwrote:
>What's the correct syntax to define a function that returns a pointer to a function? Specifically, I'd like a function that takes an int, and returns a pointer to a function that takes an int and returns a string.
I tried this:
gchar *(*f(gint n))(gint) { /* logic here */
}
but this doesn't seem to work.
:(
Define "doesn't seem to work." Are you getting a syntax error? A
runtime error? What?
f -- f
f() -- is a function
f(int n) -- that takes an integer
*f(int n) -- and returns a pointer
(*f(int n))() -- to a function
(*f(int n))(int m) -- that takes an integer
char *(*f(int n))(int m) -- and returns a char *
So, apart from the gint/gchar weirdness (I'm guessing this comes from
some API you're using), your definition looks all right to me.
char *foo(int m)
{
/* does something interesting */
}
char *bar(int m)
{
/* does something interesting */
}
char *bletch(int m)
{
/* does something interesting */
}
char *(*f(int n))(int m)
{
char *(*p)(int m);
switch(n)
{
case 0: p = foo; break;
case 1: p = bar; break;
case 2: p = bletch; break;
default: p = NULL; break;
}
return p;
}
int main(void)
{
char *result;
char *(*p)(int m);
int i;
for (i = 0; i < 4; i++)
{
p = f(i);
result = p(123);
What happens the fourth time the loop body is executed? :-)
if (result)
{
printf("result = %s\n", result);
}
}
return 0;
}
--
Army1987 (Replace "NOSPAM" with "email")
"Never attribute to malice that which can be adequately explained
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