C++ style questions (OOP)

[neo88]

Ok, here's the deal. I have a nice class definition and a whole bunch
of inline functions to go along with it in the same file. My question
is, do I need an implementation file for the class, even though I have
an inline for every single function? Or can I just use the class and
it's inlines as a header file for programs that actually use the class
and defined functions?
While I'm here I might as well ask this one too. Here is a function
that I have in the same class that I was talking about above:

inline int Startup(void) {
short quit;
std::cout << "Welcome to the Agent system Neo\n"; IO stuff
std::cout << "Do you wish to continue?(y/n)\n";
while (quit != 'y') && (quit != 'Y')
(quit != 'n') && (quit != 'N') {
if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {
Close(); // calls Close() function
}

This won't compile. The gcc says that I can't use the
short quit;
because it hasn't been declared. I don't have to declare it private
right? I tried that and it didn't work, I got the same error. How is
the loop structure, am I doing something wrong here? I also get a
parse error before 'quit' in the while loop just before the bitwise
'and' operator.
Thanks in advance for any help, it is greatly appreciated.
neo88

[Buster]

neo88 wrote:

inline int Startup(void) {
short quit;
std::cout << "Welcome to the Agent system Neo\n"; IO stuff
std::cout << "Do you wish to continue?(y/n)\n";
while (quit != 'y') && (quit != 'Y')
(quit != 'n') && (quit != 'N') {
if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {
Close(); // calls Close() function
}

This won't compile. The gcc says that I can't use the
short quit;
because it hasn't been declared.

Come on now. Didn't it really say "initialize d"?
Is it right? What value do you think "quit" has
when you first use it?

--
Regards,
Buster.

[Buster]

neo88 wrote:

inline int Startup(void) {
short quit;
std::cout << "Welcome to the Agent system Neo\n"; IO stuff
std::cout << "Do you wish to continue?(y/n)\n";
while (quit != 'y') && (quit != 'Y')
(quit != 'n') && (quit != 'N') {
if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {
Close(); // calls Close() function
}

This won't compile. The gcc says that I can't use the
short quit;
because it hasn't been declared.

Come on now. Didn't it really say "initialize d"?
Is it right? What value do you think "quit" has
when you first use it?

--
Regards,
Buster.

[Claudio Puviani]

"neo88" <so****@truevin e.net> wrote

Ok, here's the deal. I have a nice class definition
and a whole bunch of inline functions to go along
with it in the same file. My question is, do I need
an implementation file for the class, even though I
have an inline for every single function? Or can I
just use the class and it's inlines as a header file
for programs that actually use the class and
defined functions?

You could get away with just the header file, but it's good practice to have
a corresponding .cpp file, even if all it does is include the header file as
a sanity check. As your project grows, you might find that some functions,
old or new, might be better placed out-of-line or you might want to add
version information to the files in static strings or compile-time checks or
static support functions, etc.. Any changes you make in the future will then
affect how your libraries and/or applications are built. Also, unless you
comment it clearly, someone who only sees the hearder file might waste time
looking for the .cpp file. There's value in a consistent build structure.

Claudio Puviani

[Claudio Puviani]

"neo88" <so****@truevin e.net> wrote

Ok, here's the deal. I have a nice class definition
and a whole bunch of inline functions to go along
with it in the same file. My question is, do I need
an implementation file for the class, even though I
have an inline for every single function? Or can I
just use the class and it's inlines as a header file
for programs that actually use the class and
defined functions?

You could get away with just the header file, but it's good practice to have
a corresponding .cpp file, even if all it does is include the header file as
a sanity check. As your project grows, you might find that some functions,
old or new, might be better placed out-of-line or you might want to add
version information to the files in static strings or compile-time checks or
static support functions, etc.. Any changes you make in the future will then
affect how your libraries and/or applications are built. Also, unless you
comment it clearly, someone who only sees the hearder file might waste time
looking for the .cpp file. There's value in a consistent build structure.

Claudio Puviani

[Buster]

neo88 wrote:

inline int Startup(void) {
short quit;
std::cout << "Welcome to the Agent system Neo\n"; IO stuff
std::cout << "Do you wish to continue?(y/n)\n";
while (quit != 'y') && (quit != 'Y')
(quit != 'n') && (quit != 'N') {
if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {
Close(); // calls Close() function
} [...] I also get a
parse error before 'quit' in the while loop just before the bitwise
'and' operator.

The entire condition for the while loop has to be parenthesized:
while ((quit != 'y') && (quit != 'Y') &&
(quit != 'n') && (quit != 'N')) // ...

(You still need to initialize "quit" first though. Hint: there's
no way for you to do that and have the whole function still make
sense. You should remove all of the lines with "quit" in them.)

Regarding "if (std::cin << 'y')": you can't do it like that, I'm
afraid. The following is legal.

// ...
char c;
if (std::cin >> c)
{
if (c == 'y')
{
std::cout << "Please wait\n";
}
else if (c == 'n')
{
Close (); // The comment "calls Close() function"
// is worse than useless.
}
else
{
// Deal with other possible inputs.
}
}
else
{
// Deal with an input problem.
}
// ...
--
Regards,
Buster.

[Howard]

"neo88" <so****@truevin e.net> wrote in message
news:6a******** *************** ***@posting.goo gle.com...

While I'm here I might as well ask this one too. Here is a function
that I have in the same class that I was talking about above:

inline int Startup(void) {
If you include the implementation code here, there is no need for the
"inline" directive.
short quit;
std::cout << "Welcome to the Agent system Neo\n"; IO stuff
Missing comment marks here, before "IO stuff"? (Lousy comment, by the way.)
std::cout << "Do you wish to continue?(y/n)\n"; while (quit != 'y') && (quit != 'Y')
(quit != 'n') && (quit != 'N') {
Typo? There should be another "&&" between those two lines. Is there?

And why are you comparing a short (quit) against a char ('y', etc.)? Maybe
that's what that error means..there is no variable called quit that matches
the comparison against a char? (Just a guess.)

Also, the *entire* boolean expression has to be in parentheses, not just the
individual sub-expressions.
if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {
Close(); // calls Close() function
Another strange comment. Pretty obvious that Close() calls Close(), isn't
it?

But why are you calling Close() (whatever that is) inside your loop? Do you
want to "close" every time through the loop? And is there any matching Open
function?
}
Where's the rest of it? You're two closing braces short here.

This won't compile. The gcc says that I can't use the
short quit;
because it hasn't been declared.
Where does quit ever get a value assigned to it?

I don't have to declare it private right? I tried that and it didn't work, I got the same error. How is
the loop structure, am I doing something wrong here? I also get a
parse error before 'quit' in the while loop just before the bitwise
'and' operator.
That's a boolean operator, not a bitwise operator. The bitwise operator is
&, not &&.
Thanks in advance for any help, it is greatly appreciated.
neo88

[Buster]

neo88 wrote:

inline int Startup(void) {
short quit;
std::cout << "Welcome to the Agent system Neo\n"; IO stuff
std::cout << "Do you wish to continue?(y/n)\n";
while (quit != 'y') && (quit != 'Y')
(quit != 'n') && (quit != 'N') {
if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {
Close(); // calls Close() function
} [...] I also get a
parse error before 'quit' in the while loop just before the bitwise
'and' operator.

The entire condition for the while loop has to be parenthesized:
while ((quit != 'y') && (quit != 'Y') &&
(quit != 'n') && (quit != 'N')) // ...

(You still need to initialize "quit" first though. Hint: there's
no way for you to do that and have the whole function still make
sense. You should remove all of the lines with "quit" in them.)

Regarding "if (std::cin << 'y')": you can't do it like that, I'm
afraid. The following is legal.

// ...
char c;
if (std::cin >> c)
{
if (c == 'y')
{
std::cout << "Please wait\n";
}
else if (c == 'n')
{
Close (); // The comment "calls Close() function"
// is worse than useless.
}
else
{
// Deal with other possible inputs.
}
}
else
{
// Deal with an input problem.
}
// ...
--
Regards,
Buster.

[Howard]

"Howard" <al*****@hotmai l.com> wrote in message
news:c5******** @dispatch.conce ntric.net...

if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {

Oh, and I missed those lines. You can't stream data into constant
expressions. I take it you wanted to enter the data into your quit
variable, since that's what you're using to compare againt in your while
loop. You need to stream into a variable.

Howard

[Howard]

"neo88" <so****@truevin e.net> wrote in message
news:6a******** *************** ***@posting.goo gle.com...

While I'm here I might as well ask this one too. Here is a function
that I have in the same class that I was talking about above:

inline int Startup(void) {
If you include the implementation code here, there is no need for the
"inline" directive.
short quit;
std::cout << "Welcome to the Agent system Neo\n"; IO stuff
Missing comment marks here, before "IO stuff"? (Lousy comment, by the way.)
std::cout << "Do you wish to continue?(y/n)\n"; while (quit != 'y') && (quit != 'Y')
(quit != 'n') && (quit != 'N') {
Typo? There should be another "&&" between those two lines. Is there?

And why are you comparing a short (quit) against a char ('y', etc.)? Maybe
that's what that error means..there is no variable called quit that matches
the comparison against a char? (Just a guess.)

Also, the *entire* boolean expression has to be in parentheses, not just the
individual sub-expressions.
if (std::cin << 'y') {
std::cout << "Please wait\n";
} else (std::cin << 'n') {
Close(); // calls Close() function
Another strange comment. Pretty obvious that Close() calls Close(), isn't
it?

But why are you calling Close() (whatever that is) inside your loop? Do you
want to "close" every time through the loop? And is there any matching Open
function?
}
Where's the rest of it? You're two closing braces short here.

This won't compile. The gcc says that I can't use the
short quit;
because it hasn't been declared.
Where does quit ever get a value assigned to it?

I don't have to declare it private right? I tried that and it didn't work, I got the same error. How is
the loop structure, am I doing something wrong here? I also get a
parse error before 'quit' in the while loop just before the bitwise
'and' operator.
That's a boolean operator, not a bitwise operator. The bitwise operator is
&, not &&.
Thanks in advance for any help, it is greatly appreciated.
neo88