Substring problem

Keve G??bor

Hello!

In the attached example, you can see 2 textobject. The green one working fine, but the red one not.
If i change the Parameter1 Expression property to nothing from "", the red one working fine. But if the property value "", the report engine say:
Inner exception:
startIndex cannot be larger than lenght of the string
Parameter name startIndex

red Text object value:

[IIf(Length([Parameter1])>0,Substring([Parameter1],1,1),[Parameter2])]

Can you explain me, what the problem of this expression?

Thanks!

Stark

Hi , have a good day

The Error is very clear , I will try to Explain it in details :

1) This One "Substring([Parameter1],1,1)" is try to select a string from paramter1
Which start with character of index 1 and end at character of index 1

For Example :
if paramter1 = "Stark" then SubString([paramter1], 1,1) will give the result "t"
BUT
if paramter1 = "" then SubString([paramter1], 1,1) will throw an error because there is no character at Index 1 , paramter1 has Zero Characters

And in your Attachment report Parameter1 = "" , and that is why you get an error !


Solution :

you have two ways :
*) Give Paramter1 some value ,
OR
*) replace the SubString([paramter1], 1,1) With SubString([paramter1], 0,0)



Hope this help




P.S :
I didn't know what are you trying to achieve , or why paramter1 has the value "" ?

Keve G??bor

Hello Stark!

Thanks the answer!

You right! But...

I think that due the IIf condition, the Substring procedure should not be evaluate, because the Parameter1 length = 0.

The right evaluation order is:

<!--fonto:Courier New--><span style="font-family:Courier New"><!--/fonto-->IIf -> Length(Parameter1)>0 -> false -> Parameter2
-> true -> Substring(Parameter1,1,1)<!--fontc--></span><!--/fontc-->

If Parameter1 value is "" then Lenght(Parameter1) = 0.

But i think the real evaluation start within.

So, clarifying my question:
Why evaluate the Substring function the engine, if Parameter1.Lengt()==0?

[img]style_emoticons/<#EMO_DIR#>/unsure.gif" style="vertical-align:middle" emoid=":unsure:" border="0" alt="unsure.gif" /> regards, Gabor Keve[/img]

Stark wrote: »

Hi , have a good day

The Error is very clear , I will try to Explain it in details :

1) This One "Substring([Parameter1],1,1)" is try to select a string from paramter1
Which start with character of index 1 and end at character of index 1

For Example :
if paramter1 = "Stark" then SubString([paramter1], 1,1) will give the result "t"
BUT
if paramter1 = "" then SubString([paramter1], 1,1) will throw an error because there is no character at Index 1 , paramter1 has Zero Characters

And in your Attachment report Parameter1 = "" , and that is why you get an error !


Solution :

you have two ways :
*) Give Paramter1 some value ,
OR
*) replace the SubString([paramter1], 1,1) With SubString([paramter1], 0,0)



Hope this help




P.S :
I didn't know what are you trying to achieve , or why paramter1 has the value "" ?

Stark

You are welcome !

Keve G??bor wrote: »

I think that due the IIf condition, the Substring procedure should not be evaluate, because the Parameter1 length = 0.

I was think the same , Until I saw your Question , because C# didn't do that

string res = string.Empty;
string paramter1 = "";
string paramter2 = "text";
       
res = paramter1.Length > 0 ? paramter1.Substring(1, 1) : paramter2;
Console.WriteLine(res);

Keve G??bor wrote: »

So, clarifying my question:
Why evaluate the Substring function the engine, if Parameter1.Lengt()==0?

I think this is how fast report works , I really don't know much about it's engine , ( I am just a user for fast-report [img]style_emoticons/<#EMO_DIR#>/rolleyes.gif" style="vertical-align:middle" emoid=":rolleyes:" border="0" alt="rolleyes.gif" /> ) May be one of the makers can answer you ,[/img]