Unassigned local variable

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tshad

I am getting an error:

Use of unassigned local variable 'postDateRow'

But it is assigned.

Here is the code:

int payDateRow;
int postDateRow;

for(ktr=0;ktr<= rtDataBean.dataTable[0].GetUpperBound(0);ktr++)
{
mDt.Columns.Add(new DataColumn(rtDataBean.dataTable[0][ktr]));
if (rtDataBean.dataTable[0][ktr] == "Pay Date") payDateRow = ktr;
if (rtDataBean.dataTable[0][ktr] == "Post Date") postDateRow = ktr; <-
assigned here
};


for(ktr=0;ktr<= rtDataBean.dataTable.GetUpperBound(0);ktr++)
{
DataRow mDr = mDt.NewRow();
for (ktr1=0;ktr1<=rtDataBean.dataTable[0].GetUpperBound(0);ktr1++)
{
mDr[ktr1] = rtDataBean.dataTable[ktr][ktr1];
};
mDr[ktr1] = rtDataBean.dataTable[ktr][ktr1] + " / " +
rtDataBean.dataTable[ktr][postDateRow]; <- error here
mDt.Rows.Add(mDr);
};

Why is this an error?

Thanks,

Tom
 
"tshad" <[email protected]> a écrit dans le message de (e-mail address removed)...

|I am getting an error:
|
| Use of unassigned local variable 'postDateRow'
|
| But it is assigned.

No it isn't, it is only assigned *if* a condition is true.

If assignment cannot be guaranteed, you need to initialise the variable to
some default value.

Joanna
 
Joanna Carter said:
"tshad" <[email protected]> a écrit dans le message de (e-mail address removed)...

|I am getting an error:
|
| Use of unassigned local variable 'postDateRow'
|
| But it is assigned.

No it isn't, it is only assigned *if* a condition is true.

If assignment cannot be guaranteed, you need to initialise the variable to
some default value.
Click to expand...

I had thought that scalars were set by default (int=0,char='' etc).
Apparently this is not the case.

Then I assume

int postDateRow=0;

will work?

Thanks,

Tom
 
tshad,

At runtime there is no guarntees that the loop will be executed at least
once, thus no guarantee that the variables will be initialized. To make the
compiler happy give them some intialie value e.g *null* upon declaration.
 
tshad said:
I had thought that scalars were set by default (int=0,char='' etc).
Apparently this is not the case.
Click to expand...

Instance variables and static variables have default values (the
default value for a char is '\0' by the way - '' isn't a valid
character literal) but local variables don't.
 
Jon Skeet said:
Instance variables and static variables have default values (the
default value for a char is '\0' by the way - '' isn't a valid
character literal) but local variables don't.
Click to expand...

So they would be something like this?:

int static test;

Thanks,

Tom
 
tshad said:
So they would be something like this?:

int static test;
Click to expand...

Well,
static int test;
instead, but yes. (Not inside a method declaration though.)
 
Hi,

So they would be something like this?:

int static test;
Click to expand...

In addition to Jon comment you should not do this just to get it
initialized, a static member is shared to all the isntances of the class
therefore you need to keep special attention when using threads, it could
get you in trouble down the road if not used right


IMO you have to change your code, are you 100% sure that both values will
ALWAYS be present in the datatable?
What to do if this is not the case?

you could do somethign like:

int payDateRow = -1;
int postDateRow = -1;

for(ktr=0;ktr<= rtDataBean.dataTable[0].GetUpperBound(0);ktr++)
{
mDt.Columns.Add(new DataColumn(rtDataBean.dataTable[0][ktr]));
if (rtDataBean.dataTable[0][ktr] == "Pay Date") payDateRow = ktr;
if (rtDataBean.dataTable[0][ktr] == "Post Date") postDateRow = ktr;

};

if ( payDateRow <0 )
thrw new Exception( " Pay date undefined:");
if ( postDateRow <0 )
thrw new Exception( " Post date undefined:");
 
<"Ignacio Machin \( .NET/ C# MVP \)" <ignacio.machin AT
dot.state.fl.us> said:
In addition to Jon comment you should not do this just to get it
initialized, a static member is shared to all the isntances of the class
Click to expand...

Sorry to pick on you Ignacio - I know you know what's really going on
here, but I find that people get confused by the idea that a static
member is "shared to all the instances of the class". It's not that
it's shared by all the instances - it's that it's not specific to *any*
instance. It effectively belongs to the type, so it's shared whether
there are any instances or not.
 
Ignacio Machin ( .NET/ C# MVP ) said:
Hi,



In addition to Jon comment you should not do this just to get it
initialized, a static member is shared to all the isntances of the class
therefore you need to keep special attention when using threads, it could
get you in trouble down the road if not used right


IMO you have to change your code, are you 100% sure that both values will
ALWAYS be present in the datatable?
What to do if this is not the case?
Click to expand...

Yes, they will always be there.
you could do somethign like:

int payDateRow = -1;
int postDateRow = -1;
Click to expand...

I ended up doing this, but set it as 0.

Thanks,

Tom
for(ktr=0;ktr<= rtDataBean.dataTable[0].GetUpperBound(0);ktr++)
{
mDt.Columns.Add(new DataColumn(rtDataBean.dataTable[0][ktr]));
if (rtDataBean.dataTable[0][ktr] == "Pay Date") payDateRow = ktr;
if (rtDataBean.dataTable[0][ktr] == "Post Date") postDateRow = ktr;

};

if ( payDateRow <0 )
thrw new Exception( " Pay date undefined:");
if ( postDateRow <0 )
thrw new Exception( " Post date undefined:");
Click to expand...
 
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