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Reverse a String

Author

Topic

harrisw48
Starting Member

34 Posts

Posted - 2007-01-15 : 11:40:34

Any see where this is going wrong:

I always get NULLS instead of the reversed string

ALTER function dbo.backwards(@normal varchar(200))
returns varchar(200)
as
begin
declare @counter as int
declare @backwards as varchar(200)

set @counter = len(@normal)

while @counter > 0
begin
set @backwards = @backwards + substring(@normal,@counter,1)
set @counter = @counter - 1
end

return (@backwards)
end

Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)

7020 Posts

Posted - 2007-01-15 : 11:50:57

Wouldn't it be easier to use the built-in REVERSE function?

CODO ERGO SUM

jsmith8858
Dr. Cross Join

7423 Posts

Posted - 2007-01-15 : 11:51:58

Easier? Yes. l33t ? No.

- Jeff

harrisw48
Starting Member

34 Posts

Posted - 2007-01-15 : 12:01:23

It possibly would but quicker to use the REVERSE function I just wanted to know why this bit of code doesnt do what I think it should.

Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)

7020 Posts

Posted - 2007-01-15 : 12:07:24

quote:
Originally posted by harrisw48

It possibly would but quicker to use the REVERSE function I just wanted to know why this bit of code doesnt do what I think it should.

I'm sure you'll eventually figure it out. It's fairly obvious.

CODO ERGO SUM

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2007-01-15 : 12:59:11

it is?

Go with the flow & have fun! Else fight the flow

blog thingie: http://weblogs.sqlteam.com/mladenp

SwePeso
Patron Saint of Lost Yaks

30421 Posts

Posted - 2007-01-15 : 13:18:43

!ysae yreV

Peter Larsson
Helsingborg, Sweden

jsmith8858
Dr. Cross Join

7423 Posts

Posted - 2007-01-15 : 13:18:47

@backwards is never set to an initial value; thus, it is NULL and appending anything to NULL results in: Null.

- Jeff

Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)

7020 Posts

Posted - 2007-01-15 : 13:36:48

This should fix it:

ALTER function dbo.backwards(@normal varchar(200))
returns varchar(200)
as
begin
return reverse(@normal)
end

CODO ERGO SUM

Alan Schofield
Starting Member

23 Posts

Posted - 2007-01-16 : 11:12:03

Yep, just add SET @Backwards = '' before you do any processing on it....

Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)

7020 Posts

Posted - 2007-01-16 : 12:06:25

quote:
Originally posted by Alan Schofield

Yep, just add SET @Backwards = '' before you do any processing on it....

Unless, of course, the input parameter @normal is null...

CODO ERGO SUM

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