passing character to function.

[kalinga1234@gmail.com]

there is a problem regarding passing array of characters to another
function(withou t using structures,poin ter etc,).can anybody help me to
solve the problem.

[Srini]

Re: passing character to function.

> there is a problem regarding passing array of characters to another[color=blue]
> function(withou t using structures,poin ter etc,).can anybody help me to
> solve the problem.[/color]

What problem??

void fun(char arr[]) {
// ...
}

char arr[10];
// ...
fun(arr);

Srini

[John Harrison]

Re: passing character to function.

kalinga1234@gma il.com wrote:[color=blue]
> there is a problem regarding passing array of characters to another
> function(withou t using structures,poin ter etc,).can anybody help me to
> solve the problem.
>[/color]

Passing arrays is not allowed in C++. You must use pointers or
references or structs or classes. There is no other way to do it.

There best way would be to use the C++ string class.

john

[Greg]

Re: passing character to function.

John Harrison wrote:[color=blue]
> kalinga1234@gma il.com wrote:[color=green]
> > there is a problem regarding passing array of characters to another
> > function(withou t using structures,poin ter etc,).can anybody help me to
> > solve the problem.
> >[/color]
>
> Passing arrays is not allowed in C++. You must use pointers or
> references or structs or classes. There is no other way to do it.
>
> There best way would be to use the C++ string class.
>
> john[/color]

It's legal to pass an array in a function call, it's just not possible
for the function called to recover it. In C++ an array passed by value
"decays" into a pointer to its first element by the time the receiver
gets it.

One workaround is to pass the array by reference. In fact passing by
reference is often a better idea than passing it by value, even if it
were possible to do so:

void f( int (&inArrayRef)[5]);

int main()
{
int firstArray[5];
int secondArray[7];

f( firstArray); // ok
f( secondArray); // error - wrong size
}

Greg

[Jack Klein]

Re: passing character to function.

On 16 Sep 2005 05:10:33 -0700, "Greg" <greghe@pacbell .net> wrote in
comp.lang.c++:
[color=blue]
> John Harrison wrote:[color=green]
> > kalinga1234@gma il.com wrote:[color=darkred]
> > > there is a problem regarding passing array of characters to another
> > > function(withou t using structures,poin ter etc,).can anybody help me to
> > > solve the problem.
> > >[/color]
> >
> > Passing arrays is not allowed in C++. You must use pointers or
> > references or structs or classes. There is no other way to do it.
> >
> > There best way would be to use the C++ string class.
> >
> > john[/color]
>
> It's legal to pass an array in a function call, it's just not possible[/color]

No, it is not. It is one of Dennis Ritchie's few unfortunate lapses
in judgment. The name of an array, in all contexts except when used
as the operand of the sizeof operator, is converted to a pointer to
its first element. It is literally impossible to pass a naked array
by value.
[color=blue]
> for the function called to recover it. In C++ an array passed by value
> "decays" into a pointer to its first element by the time the receiver
> gets it.[/color]

It has nothing to do with "when the receiver gets it". The receiver
receives exactly what the function definition specifies, and when you
write a definition with a parameter of type TYPE array[], you are
actually defining a parameter of type TYPE *array. The conversion
happens in the caller, the array is never passed.

It is unfortunate that this syntax was ever allowed in a function
declaration. It has added to the confusion between pointers and
arrays in C and C++ for more than 30 years. And it leads to erroneous
statements like "it's legal to pass an array in a function call",
which help perpetuate the confusion.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++

http://www.contrib.andrew.cmu.edu/~ajo/docs/FAQ-acllc.html

[Alf P. Steinbach]

Re: passing character to function.

* Jack Klein:[color=blue]
> * Greg:[color=green]
> > * John Harrison:[color=darkred]
> > > * kalinga1234@gma il.com:
> > > > there is a problem regarding passing array of characters to another
> > > > function(withou t using structures,poin ter etc,).can anybody help me to
> > > > solve the problem.
> > >
> > > Passing arrays is not allowed in C++. You must use pointers or
> > > references or structs or classes. There is no other way to do it.
> > >
> > > There best way would be to use the C++ string class.[/color]
> >
> > It's legal to pass an array in a function call[/color]
>
> No, it is not. It is one of Dennis Ritchie's few unfortunate lapses
> in judgment. The name of an array, in all contexts except when used
> as the operand of the sizeof operator, is converted to a pointer to
> its first element.[/color]

Additional exception: when used as an initializer for an array reference.

Are there more exceptions?

Someone else dig into the standard, please; me, I want a cup of coffee now.

[color=blue]
> It is literally impossible to pass a naked array by value.[/color]

In C.

In C++ we can do it, by passing the array by reference:

typedef double Triple[3];
void foo( Triple const& xyz );

But at the cost of either limiting ourselves to just one size of array, or
else using the template mechanism (which might result in duplicated code).

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Alf P. Steinbach]

Re: passing character to function.

* Alf P. Steinbach:[color=blue]
> * Jack Klein:[color=green]
> > * Greg:[color=darkred]
> > > * John Harrison:
> > > > * kalinga1234@gma il.com:
> > > > > there is a problem regarding passing array of characters to another
> > > > > function(withou t using structures,poin ter etc,).can anybody help me to
> > > > > solve the problem.
> > > >
> > > > Passing arrays is not allowed in C++. You must use pointers or
> > > > references or structs or classes. There is no other way to do it.
> > > >
> > > > There best way would be to use the C++ string class.
> > >
> > > It's legal to pass an array in a function call[/color]
> >
> > No, it is not. It is one of Dennis Ritchie's few unfortunate lapses
> > in judgment. The name of an array, in all contexts except when used
> > as the operand of the sizeof operator, is converted to a pointer to
> > its first element.[/color]
>
> Additional exception: when used as an initializer for an array reference.
>
> Are there more exceptions?
>
> Someone else dig into the standard, please; me, I want a cup of coffee now.
>
>[color=green]
> > It is literally impossible to pass a naked array by value.[/color]
>
> In C.
>
> In C++ we can do it, by passing the array by reference:
>
> typedef double Triple[3];
> void foo( Triple const& xyz );
>
> But at the cost of either limiting ourselves to just one size of array, or
> else using the template mechanism (which might result in duplicated code).[/color]

Sorry, I didn't mean that pass-by-reference is pass-by-value: I meant, the
array is not converted to a pointer in this case, which is what matters.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Kai-Uwe Bux]

Re: passing character to function.

Jack Klein wrote:
[color=blue]
> On 16 Sep 2005 05:10:33 -0700, "Greg" <greghe@pacbell .net> wrote in
> comp.lang.c++:
>[/color]
[snip][color=blue][color=green]
>>
>> It's legal to pass an array in a function call, it's just not possible[/color]
>
> No, it is not. It is one of Dennis Ritchie's few unfortunate lapses
> in judgment. The name of an array, in all contexts except when used
> as the operand of the sizeof operator, is converted to a pointer to
> its first element. It is literally impossible to pass a naked array
> by value.
>[color=green]
>> for the function called to recover it. In C++ an array passed by value
>> "decays" into a pointer to its first element by the time the receiver
>> gets it.[/color]
>
> It has nothing to do with "when the receiver gets it". The receiver
> receives exactly what the function definition specifies, and when you
> write a definition with a parameter of type TYPE array[], you are
> actually defining a parameter of type TYPE *array. The conversion
> happens in the caller, the array is never passed.
>
> It is unfortunate that this syntax was ever allowed in a function
> declaration. It has added to the confusion between pointers and
> arrays in C and C++ for more than 30 years. And it leads to erroneous
> statements like "it's legal to pass an array in a function call",
> which help perpetuate the confusion.[/color]

You made me curious.

Is there an observable difference in what you write and what Greg hinted at?
For the sake of this discussion, let us suppose there was a language B++
that is identical to C++ except that it uses Greg's way of passing arrays.
Does there exist a program that behaves differently when interpreted as C++
and when interpreted as B++?

[There is this funny thing that the admissible moves of a knight in chess
can be given by different rules:

(a) a knight jumps as though it moved two fields vertically or horizontally
and then one field in a perpendicular direction.

(b) a knight jumps as though it moved one field vertically or horizontally
and then two fields in a perpendicular direction.

(c) a knight jumps as though it moves one field in a diagonal direction and
then one field in a horizontal or vertical direction so that it will not
end on a field neighboring its initial position.

....

On an 8x8 chess board, these rules are provably equivalent. I just wonder if
you and Greg might conincidentally describe the same thing in different
words, where yours just happen to be closer to the wording of the
standard.]


Best

Kai-Uwe Bux

[Greg]

Re: passing character to function.

Jack Klein wrote:[color=blue]
> On 16 Sep 2005 05:10:33 -0700, "Greg" <greghe@pacbell .net> wrote in
> comp.lang.c++:
>[color=green]
> > John Harrison wrote:[color=darkred]
> > > kalinga1234@gma il.com wrote:
> > > > there is a problem regarding passing array of characters to another
> > > > function(withou t using structures,poin ter etc,).can anybody help me to
> > > > solve the problem.
> > > >
> > >
> > > Passing arrays is not allowed in C++. You must use pointers or
> > > references or structs or classes. There is no other way to do it.
> > >
> > > There best way would be to use the C++ string class.
> > >
> > > john[/color]
> >
> > It's legal to pass an array in a function call, it's just not possible[/color]
>
> No, it is not. It is one of Dennis Ritchie's few unfortunate lapses
> in judgment. The name of an array, in all contexts except when used
> as the operand of the sizeof operator, is converted to a pointer to
> its first element. It is literally impossible to pass a naked array
> by value.
>[color=green]
> > for the function called to recover it. In C++ an array passed by value
> > "decays" into a pointer to its first element by the time the receiver
> > gets it.[/color]
>
> It has nothing to do with "when the receiver gets it". The receiver
> receives exactly what the function definition specifies, and when you
> write a definition with a parameter of type TYPE array[], you are
> actually defining a parameter of type TYPE *array. The conversion
> happens in the caller, the array is never passed.
>
> It is unfortunate that this syntax was ever allowed in a function
> declaration. It has added to the confusion between pointers and
> arrays in C and C++ for more than 30 years. And it leads to erroneous
> statements like "it's legal to pass an array in a function call",
> which help perpetuate the confusion.
>
> --
> Jack Klein[/color]

Being legal is not the same as being possible.

I think it is more confusing to state that passing an array to a
function is illegal in C++, even though code that does so compiles
without so much as a warning, and executes without a problem. One could
easily wonder how many other illegal statements a C++ compiler accepts,
and that work as well as this one.

It is clearer in my mind simply to state that it is not possible in C++
to pass an array intact in a function call. All that such an attempt
accomplishes is to pass a pointer. Therefore it is a deficit in the
syntax of the language that makes passing an array by value impossible.
In light of that fact, deciding whether such an operation - if it could
be expressed - would be legal or not, seems a little pointless.

Greg