obj function hello()

[gert]

#include <stdio.h>

obj function hello(){
struct obj = { char *data = 'hello'}
obj.add = obj_add(obj);
return obj;
}

void function obj_add(obj){
obj function add(value){
obj.data += value;
return obj;
}
}

void main(){
test = hello();
test.add('world ');
printf(test.dat a);
}

I don't know much c and i was hoping the code above was pointing out
what i am trying to do ?

[Ian Collins]

gert wrote:

>
One last sub question, is this a good way to make programs in C by
defining a struct and assign function pointers to it to make it look
like a oo. Or are there other recommended methods to make a program.

It's perfectly acceptable if an OO solution fits your problem. It is a
common style for drivers that have to implement a set of interfaces
defined by an operating system.

--
Ian Collins.

[Christopher Benson-Manica]

gert <ge**********@g mail.comwrote:

One last sub question, is this a good way to make programs in C by
defining a struct and assign function pointers to it to make it look
like a oo. Or are there other recommended methods to make a program.

IMHO, you'll do a lot better by adapting to C's paradigm rather than
trying to make it look and feel like Python. For simple programs
there's certainly no call for anything OO.

--
C. Benson Manica | I *should* know what I'm talking about - if I
cbmanica(at)gma il.com | don't, I need to know. Flames welcome.

[gert]

#include <stdio.h>
#include <stdlib.h>

typedef struct self{
int value;
int (*add)(struct self*,int);
} Obj;

int add(Obj* this, int val) {
this->value = val;
return this->value;
}

int main (int argc, char* argv[]){
Obj* myobj = malloc(sizeof *myobj);
myobj->value = 0;
myobj->add = add;
myobj->add(myobj, 42);
printf("%d\n", myobj->value);
return 0;
}

I modified the example a bit to give it a more oo look but i still
having trouble understanding the memory allocation part ?
Obj* myobj = malloc(sizeof *myobj);

for me it would make more sense if i would wright
Obj* myobj = malloc(sizeof myobj);

The thing is they both give the same output :)

[Christopher Benson-Manica]

gert <ge**********@g mail.comwrote:

I modified the example a bit to give it a more oo look but i still
having trouble understanding the memory allocation part ?

Obj* myobj = malloc(sizeof *myobj);

for me it would make more sense if i would wright
Obj* myobj = malloc(sizeof myobj);

Why? myobj is a *pointer* - you want enough memory for myobj to point
to an Obj, not however much memory the pointer takes up. This is a
crucial difference.

The thing is they both give the same output :)

Only because you seem to be lucky - the second version is wrong, and
either happens to allocate enough space for an Obj (implying
sizeof(Obj) < sizeof(Obj*)) or accesses memory it has no right to
access.

--
C. Benson Manica | I *should* know what I'm talking about - if I
cbmanica(at)gma il.com | don't, I need to know. Flames welcome.

[gert]

On Feb 9, 9:41 pm, Christopher Benson-Manica
<[e-mail] eshell.orgwrote :

gert <gert.cuyk...@g mail.comwrote:

I modified the example a bit to give it a more oo look but i still
having trouble understanding the memory allocation part ?
Obj* myobj = malloc(sizeof *myobj);
for me it would make more sense if i would wright
Obj* myobj = malloc(sizeof myobj);

Why? myobj is a *pointer* - you want enough memory for myobj to point
to an Obj, not however much memory the pointer takes up. This is a
crucial difference.

The thing is they both give the same output :)

Only because you seem to be lucky - the second version is wrong, and
either happens to allocate enough space for an Obj (implying
sizeof(Obj) < sizeof(Obj*)) or accesses memory it has no right to
access.

Ok i see, i have to allocate memory for myobj not the pointer it self

[Ian Collins]

Christopher Benson-Manica wrote:

gert <ge**********@g mail.comwrote:

>>One last sub question, is this a good way to make programs in C by
defining a struct and assign function pointers to it to make it look
like a oo. Or are there other recommended methods to make a program.

IMHO, you'll do a lot better by adapting to C's paradigm rather than
trying to make it look and feel like Python. For simple programs
there's certainly no call for anything OO.

I agree, but there is a fairly large C domain, which includes drivers
and streams, where this 'pseudo OO' paradigm is idiomatic.

--
Ian Collins.

[Malcolm McLean]

"gert" <ge**********@g mail.comwrote in message

>
One last sub question, is this a good way to make programs in C by
defining a struct and assign function pointers to it to make it look
like a oo. Or are there other recommended methods to make a program.

A C program should normally be a structured program.
That is to say, there should be one entry function at the top, as is
required by C and called "main", which calls subroutines which call further
subroutines in a roughly balanced way - "main" is not a long list of calls,
nor do subroutines call each other in a daisy chain.

We stretch the paradigm when we allow recursive functions, mutually
recursive functions, and indirect calls through function pointers.

Object-oriented design, on the other hand, relies very heavily on function
pointers to bind the call at a late stage, often at runtime. Though you can
do object-oriented design in C, the language provides very little support
for it. Just as a couple of Latin phrases won't turn an English text into a
Latin one, a spot of late binding through function pointers can be useful in
C programs. However if you are building the whole program around such
interfaces, really you ought to use C++ or another language.

[fdmfdmfdm]

On Feb 8, 5:02 pm, "gert" <gert.cuyk...@g mail.comwrote:

#include <stdio.h>

obj function hello(){
struct obj = { char *data = 'hello'}
obj.add = obj_add(obj);
return obj;

}

void function obj_add(obj){
obj function add(value){
obj.data += value;
return obj;
}

}

void main(){
test = hello();
test.add('world ');
printf(test.dat a);

}

I don't know much c and i was hoping the code above was pointing out
what i am trying to do ?

To write something like Java or C++ in C, you need to define a lot of
structure, maybe some #define and typedef. Why don't you use Java or C+
+ instead?

[gert]

On Feb 9, 10:00 pm, "Malcolm McLean" <regniz...@btin ternet.comwrote :

A C program should normally be a structured program.
That is to say, there should be one entry function at the top, as is
required by C and called "main", which calls subroutines which call further
subroutines in a roughly balanced way - "main" is not a long list of calls,
nor do subroutines call each other in a daisy chain.

We stretch the paradigm when we allow recursive functions, mutually
recursive functions, and indirect calls through function pointers.

Object-oriented design, on the other hand, relies very heavily on function
pointers to bind the call at a late stage, often at runtime. Though you can
do object-oriented design in C, the language provides very little support
for it. Just as a couple of Latin phrases won't turn an English text into a
Latin one, a spot of late binding through function pointers can be useful in
C programs. However if you are building the whole program around such
interfaces, really you ought to use C++ or another language.

#include <stdio.h>
#include <stdlib.h>

typedef struct self{
int value;
int (*add)(struct self*,int);
} obj;

int add(obj* this, int val) {
this->value = val;
return this->value;
}

obj* Obj(void){
obj* new = malloc(sizeof *new);
new->value = 0;
new->add = add;
return new;
}

int main (int argc, char** argv){
obj* myobj=Obj();
myobj->add(myobj,7) ;
printf("%d\n", myobj->value);
return 0;
}

But you have to admit it looks nice this way not ?

[gert]

On Feb 9, 10:30 pm, "fdmfdm...@gmai l.com" <fdmfdm...@gmai l.comwrote:

To write something like Java or C++ in C, you need to define a lot of
structure, maybe some #define and typedef. Why don't you use Java or C+
+ instead?

I started with php then went to javascript and python making me
realise you can do the same with more basic syntax, so why not try to
do it c. I think if you can pull it off in c you can pull it of in any
language :)