Re: unable to use a local variable
> its also horrible programming practice to do it the way you have.
> its best to declare all the variables you need at the top, and,
> give them values below. in rare cases,
I don't think it is a *horrible* programming practice to declare your
variables where you use them (assuming you are using C++ ofcourse).
If I had a function that was 150 lines long, and I need a local variable
near the end, why would I declare it at the top of the function (or block)?
That would require the programmer that comes in after me to remember how the
variable was declared at the top of the block, and if he forgot, he would
have to scroll back up to see how it was declared. One other point is that
it keeps another programmer from coming in and using the variable assuming
that it is already setup correctly. For example.
void test( void )
{
// Non meaningfule value, just an initiailizer.
int a = 0;
// Maintnance programmer inserts line here.
a += 20; // Wants 120, but gets 20.
// Intial meaningful value
a = 100;
}
The code snippet is meaningless in itself, but the scenario can happen
happen. If *a* were declared where it was used, the compiler would throw
out an error long before a bug was introduced.
So is it so horrible?
Brad
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Re: unable to use a local variable
Blackwell Chris A Maj CENTAF-PSAB/C3 TCT Attack Coordinator <[EMAIL PROTECTED]> wrote:
>
> Hate to ask this "stupid" question but my sanity has overcome my ego...
>
> I am working with the Code Warrior Palm OS SDK 4.0.
>
> I've stuck mostly with the loaded template and started to add on a few
> proceedures. I'm trying to use a local variable and its causing an
> "Expression Syntax Error" on the next variable declaration. Ie:
>
> void DBManualEntry()
> {
>Err er;
>UInt16 position=13;
>//position+=11;
>
>MemHandle vh=MemHandleNew(3);
>MemPtr npos = MemHandleLock(vh);
>
>ListBoxStrType *payments = MemPtrNew(sizeof(ListBoxStrType));
>
>
> }
>
> If I let "position+=11;" compile, I will get an Expression Syntax Error on
> the next line "MemHandle vh..."
>
> I've been teaching myself with a book and I just keep missing this part.
> Huge thanks for any help.
>
First comment: get a better book to teach yourself C.
In C any executable statements (like your position += 11) have to follow
the local variable declarations in your function (here DBManualEntry).
You are confused by the fact that declaration statements can have
initialization clauses.
In fact all the statements you quote are declarations (local variables:
er, vh, position, npos, payments).
So the 'position+=11;' statement should be just before (or after) the
.
Good luck with teaching yourself C.
PalmOS programming is yet an other kettle of fish ...
Ton van Overbeek
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Re: unable to use a local variable
> I am working with the Code Warrior Palm OS SDK 4.0.
probably best not to mention it like that, you normally have a release
of codewarrior (r5,6,7,8 or 9) and, the SDK release. the SDK release
can be used in any codewarrior version by default. the codewarrior
compiler version is probably more important than the SDK version :)
> I've stuck mostly with the loaded template and started to add on a few
> proceedures. I'm trying to use a local variable and its causing an
> "Expression Syntax Error" on the next variable declaration. Ie:
>
> void DBManualEntry()
> {
> Err er;
> UInt16 position=13;
> //position+=11;
>
> MemHandle vh=MemHandleNew(3);
> MemPtr npos = MemHandleLock(vh);
yes, thats standard C rules. you are not allowed to create a new
declaration for a variable once you have started writing statements
that operate on declarations.
its also horrible programming practice to do it the way you have.
its best to declare all the variables you need at the top, and,
give them values below. in rare cases, you may be tempted to use
a code block for counter variables etc, or variables more specific
to a branch of the code, ie:
x += 13;
{
MemHandle y;
y = ...;
}
you can check this up in more detail by looking at the 1990 ISO C
standard, which specifically tells you:
"... all variables be declared at the start of a scope block."
> I've been teaching myself with a book and I just keep missing this part.
> Huge thanks for any help.
start of here:
http://www.lysator.liu.se/c/bwk-tutor.html
never hurts to go over your C again :) and Kernighan is always a
good start when it comes to catching up on your C :P
---
Aaron Ardiri [EMAIL PROTECTED]
CEO - CTO +46 70 656 1143
Mobile Wizardry http://www.mobilewizardry.com/
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Re: unable to use a local variable
> void DBManualEntry()
> {
> Err er;
> UInt16 position=13;
> //position+=11;
>
> MemHandle vh=MemHandleNew(3);
> MemPtr npos = MemHandleLock(vh);
>
> ListBoxStrType *payments = MemPtrNew(sizeof(ListBoxStrType));
>
>
> }
>
> If I let "position+=11;" compile, I will get an Expression Syntax
> Error on the next line "MemHandle vh..."
Just a guess, but are you compiling a C++ file, or straight C? C++ will let
you get away with what you're doing there, but C won't. C needs to see all
declarations of variables before any executable code in a given function.
The following should compile even under a C compiler:
void DBManualEntry()
{
Err er;
UInt16 position=13;
MemHandle vh;
MemPtr npos;
ListBoxStrType *payments;
position+=11;
vh=MemHandleNew(3);
npos = MemHandleLock(vh);
payments = MemPtrNew(sizeof(ListBoxStrType));
}
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unable to use a local variable
Hate to ask this "stupid" question but my sanity has overcome my ego...
I am working with the Code Warrior Palm OS SDK 4.0.
I've stuck mostly with the loaded template and started to add on a few
proceedures. I'm trying to use a local variable and its causing an
"Expression Syntax Error" on the next variable declaration. Ie:
void DBManualEntry()
{
Err er;
UInt16 position=13;
//position+=11;
MemHandle vh=MemHandleNew(3);
MemPtr npos = MemHandleLock(vh);
ListBoxStrType *payments = MemPtrNew(sizeof(ListBoxStrType));
}
If I let "position+=11;" compile, I will get an Expression Syntax Error on
the next line "MemHandle vh..."
I've been teaching myself with a book and I just keep missing this part.
Huge thanks for any help.
Chris
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