C++ array relative C question

[hpy_awad]

I know that group is for C not for C++ but please try to help me ,
How can I declare size of an array as variable value came from screen?

#include "iostream.h "
#include "iomanip.h"
#include "conio.h"
float ArraySum(float Array[],int ArraySize);
int main()
{
clrscr();
int ArraySize=0;
// Read the array elements
cout << "Enter Array Size : " ;
cin >> ArraySize;
^^^^^^^^^^^^^^^ ^^^^^^
float Array[ArraySize];
^^^^^^^^^^^^^^^ ^^^^^^^^
cout <<endl<< "Enter Array Elements " ;
for (int i=0;i<=ArraySiz e;i++)
{
cout <<endl<< "Enter elements no " << i << " : ";
cin >> Array[i];
}
cout <<endl << "The sum of the elements values :" << setw(5) <<
ArraySum(Array, ArraySize);
return 0;
}

float ArraySum(float arr[],int n)
{
int total=0;
for (int i=0;i<=n;i++)
total+=arr[i];
return total;
}

[Mark A. Odell]

eh***********@y ahoo.com (hp******@yahoo .com) wrote in
news:7e******** *************** ***@posting.goo gle.com:

I know that group is for C not for C++ but please try to help me ,
How can I declare size of an array as variable value came from screen?

You cannot. You must malloc() the memory and use a pointer instead of an
array. E.g.

float *pArray = malloc(ArraySiz e * sizeof *pArray);

--
- Mark ->
--

[Michael Mair]

Hi there,

I know that group is for C not for C++ but please try to help me ,
The question is: What do you want to do?
Do you want to do it in C++, C89, C99?
We can help you only with the last two -- and, topically, only
with portable code.

How can I declare size of an array as variable value came from screen?
In all three languages: malloc() (and free())
C++: new (and delete)
C89: malloc() (and free())
C99: malloc() (and free()), variable length array

#include "iostream.h "
#include "iomanip.h"
#include "conio.h"
float ArraySum(float Array[],int ArraySize);
int main()
{
clrscr();
int ArraySize=0; note: use size_t for everything you want to use as array index // Read the array elements
cout << "Enter Array Size : " ;
cin >> ArraySize;
^^^^^^^^^^^^^^^ ^^^^^^
float Array[ArraySize];
^^^^^^^^^^^^^^^ ^^^^^^^^ in C99, this line is perfectly valid
C89:
float *Array;
at beginning of main() with the other declarations, and
Array = malloc(ArraySiz e * sizeof *Array);
if (Array == NULL) {
/* Handle error, usually exit(EXIT_FAILU RE). */
}
and at the end -- or as soon as you no longer need the memory
Array is now pointing to --
free(Array); cout <<endl<< "Enter Array Elements " ;
for (int i=0;i<=ArraySiz e;i++)
{
cout <<endl<< "Enter elements no " << i << " : ";
cin >> Array[i];
}
cout <<endl << "The sum of the elements values :" << setw(5) <<
ArraySum(Array, ArraySize);
return 0;
}

float ArraySum(float arr[],int n)
{
int total=0;
for (int i=0;i<=n;i++)
total+=arr[i];
return total;
}

Note: For C99 VLAs, there are special options when passing them
as arguments.
If you can specify your needs somewhat clearer, we can help you
better.
It would also be better to give us C code instead of C++ code.
Cheers
Michael

[Dave]

hp******@yahoo. com wrote:

I know that group is for C not for C++ but please try to help me ,

Suppose you were in a Maths class, and the lecturer asked "Any
questions?" and someone piped up "I have this question about my Physics
homework."

It's not a case of whether or not the mathematicians present know
physics; in many cases they will, but they are there to discuss Maths,
not Physics, and the latter is a waste of everyone's time.

As is discussing C++ in comp.lang.c. Does your newsgroup software
somehow not have access to comp.lang.c++?

C and C++ are substantially different languages, even though they both
begin with the same letter (like C and Cobol, or PL/1 and PL/SQL), and
discussions about the details of one can develop into substantial
bandwidth hogs, even if this wasn't intended by the OP, so please
restrict your posting to On Topic items only.

Dave.

[Martin Ambuhl]

hp******@yahoo. com wrote:

I know that group is for C not for C++
So why not post to comp.lang.c++, where C++ is topical.
but please try to help me ,
How can I declare size of an array as variable value came from screen?
The OP's code is quoted at EOM. Here is a rewrite. Note that many
current implementations will not like it. Luckily, the comp.lang.c FAQ
and all texts for beginners give full explanations of the way to do this
that works for all C compilers.

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

double ArraySum(double Array[], int ArraySize);

int main()
{
unsigned ArraySize = 0, i;
printf("Enter Array Size: ");
fflush(stdout);
scanf("%u", &ArraySize); /* see the FAQ for better ways to do
input safely */
double Array[ArraySize]; /* With many C compilers this will not
work. If using ISO C89, declare the
pointer-to-double Array at the top
of the block, malloc the space,
checking the return value. You may
find that preferable even if the
code given works. The FAQ gives good
coverage to the right way to do
that, as will any elementary text
for beginning programmers.

Notice that the broken "<=" in the
loop below and in ArraySum are
fixed. */
printf("Enter Array Elements ..\n");
for (i = 0; i < ArraySize; i++) {
printf(" Elements #%u: ", i);
scanf("%lg", &Array[i]); /* see the FAQ for better ways to
do input safely */
}
printf("The sum of the elements values : %g\n",
ArraySum(Array, ArraySize));
return 0;
}

double ArraySum(double arr[], int n)
{
int total = 0, i;
for (i = 0; i < n; i++)
total += arr[i];
return total;
}

#include "iostream.h "
#include "iomanip.h"
#include "conio.h"
float ArraySum(float Array[],int ArraySize);
int main()
{
clrscr();
int ArraySize=0;
// Read the array elements
cout << "Enter Array Size : " ;
cin >> ArraySize;
^^^^^^^^^^^^^^^ ^^^^^^
float Array[ArraySize];
^^^^^^^^^^^^^^^ ^^^^^^^^
cout <<endl<< "Enter Array Elements " ;
for (int i=0;i<=ArraySiz e;i++)
{
cout <<endl<< "Enter elements no " << i << " : ";
cin >> Array[i];
}
cout <<endl << "The sum of the elements values :" << setw(5) <<
ArraySum(Array, ArraySize);
return 0;
}

float ArraySum(float arr[],int n)
{
int total=0;
for (int i=0;i<=n;i++)
total+=arr[i];
return total;
}

[Karthik Kumar]

hp******@yahoo. com wrote:

I know that group is for C not for C++ but please try to help me ,
How can I declare size of an array as variable value came from screen?
From your comments, it seems like you are writing C++ code.
Hence setting follow-up to c.l.c++ .

#include "iostream.h "
#include "iomanip.h"
They are deprecated headers as far as C++ is concerned.

#include <iostream>
#include <iomanip>


#include "conio.h"
This is non-standard header.
float ArraySum(float Array[],int ArraySize);
int main()
{
clrscr();
int ArraySize=0;
// Read the array elements
cout << "Enter Array Size : " ;
The compiler (C++ ) would have flagged an error here since
cout belongs to std namespace.

cin >> ArraySize;
Ditto for cin again.
^^^^^^^^^^^^^^^ ^^^^^^
float Array[ArraySize];
^^^^^^^^^^^^^^^ ^^^^^^^^

Nope. Use dynamic memory allocation.
cout <<endl<< "Enter Array Elements " ;
for (int i=0;i<=ArraySiz e;i++)
{
cout <<endl<< "Enter elements no " << i << " : ";
cin >> Array[i];
}
cout <<endl << "The sum of the elements values :" << setw(5) <<
ArraySum(Array, ArraySize);
return 0;
}

float ArraySum(float arr[],int n)
{
int total=0;
for (int i=0;i<=n;i++)
Please use size_t for array indices.
total+=arr[i];
return total;
}

--
Karthik.
http://akktech.blogspot.com .

[Default User]

hp******@yahoo. com wrote:

I know that group is for C not for C++ but please try to help me ,

Why? What is wrong with comp.lang.c++?


Brian Rodenborn

[Mabden]

"Dave" <re************ *@elcaro.moc> wrote in message
news:ii******** ****@news.oracl e.com...

hp******@yahoo. com wrote:

I know that group is for C not for C++ but please try to help me ,
Suppose you were in a Maths class, and the lecturer asked "Any
questions?" and someone piped up "I have this question about my

Physics homework."

It's not a case of whether or not the mathematicians present know
physics; in many cases they will, but they are there to discuss Maths,
not Physics, and the latter is a waste of everyone's time.

As is discussing C++ in comp.lang.c. Does your newsgroup software
somehow not have access to comp.lang.c++?

C and C++ are substantially different languages, even though they both
begin with the same letter (like C and Cobol, or PL/1 and PL/SQL), and
discussions about the details of one can develop into substantial
bandwidth hogs, even if this wasn't intended by the OP, so please
restrict your posting to On Topic items only.

Maths? There's more than one?
We just call it Math on this continent.

--
Mabden

[Mabden]

"Default User" <fi********@boe ing.com.invalid > wrote in message
news:I5******** @news.boeing.co m...

hp******@yahoo. com wrote:

I know that group is for C not for C++ but please try to help me ,

Why? What is wrong with comp.lang.c++?

Well, don't _even_ get me started about THOSE pricks!

;-)

--
Mabden
p.s. These are the jokes, folks...
p.p.s. I know you're there, I can hear you breathing.

[Michael Mair]

Mabden wrote:

"Dave" <re************ *@elcaro.moc> wrote

Suppose you were in a Maths class,

[snip]
Maths? There's more than one?
We just call it Math on this continent.

Look it up. It is called mathematics, short maths
(add scary capital letters when needed), as a subject as well as
a discipline. I find "math [Amer.] [ifml.]: maths" when looking
up "math"...

I do not know which continent you are from but I guess that
you did not pay attention in your *English* class.

--Michael