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Hi Mark,
I'm really glad you included the source code... it made it easy for
me to understand what you needed help with!
First of all, lets take a look at your prototype... Note that you
are passing your parameters by REFERENCE as opposed to passing it
by VALUE. Passing by reference is the default method, and its
certainly the one that I prefer for passing strings, since its
faster, and you can return changes to the string and have it be
changed in the calling routine. However, please understand that
this means that the compiler is actually passing the ADDRESS
in main storage to your procedure, *NOT* the values of the bytes
that are stored there!
So, when you pass "dsshpnm" to the Center sub-proc, what its
actually receiving is a pointer to the start of the area of memory
where dsshpnm is stored.
Next, you're using the MOVEA op-code to move instring to work_arr.
Since instring is defined as 256 bytes long, you're actually
telling the computer to move "256 bytes, starting at the
address of the dsshpnm variable"
Do you see why this results in you passing the remainder of the
data structure? If you look more closely, you'll probably see
that its also passing additional data after your data structure,
since the DS is only 155 bytes long, but instring is 256!
A few things pop into my mind. First, its important that when
you use OPTIONS(*VARSIZE) that you find out the length of the
original variable thats being passed, and make sure you ONLY use
THAT MUCH of the variable. (Imagine if you were changing the
data that was passed! If you're not careful, you could end up
accidentally changing the values of other variables in memory!!!)
Presumably, this is why you're passing the Len parameter to begin
with!
Second, you could simply remove the options(*varsize) from your
prototype/interface. What good is it really doing you? This way,
you could use "instring" as a 256 byte string without any problems.
Third, if you do want to use options(*varsize) you could use an
operational descriptor to get the string length, and then make
sure that you only reference that length of data...
Here's an example of this:
D* Note the OPDESC keyword, this tells the calling routine to
D* pass an operational descriptor for each parameter...
D Center PR 256A OPDESC
D instring 256A Const Options(*varsize)
D* I'm at V3R2, and so I can't directly reference "shiptods"
D* in the overlay statements. However, the way you were
D* doing it should work fine...
D shiptods ds
D dswhole 155
D dsshpnm 35 overlay(dswhole:1)
D dsship1 35 overlay(dswhole:36)
D dsship2 35 overlay(dswhole:71)
D dsship3 35 overlay(dswhole:106)
D dsshpst 2 overlay(dswhole:141)
D dsshpzp 10 overlay(dswhole:143)
D dsshpco 3 overlay(dswhole:153)
C* test the center sub-proc
c eval dsshpnm = 'CENTER ME'
c eval output = Center(dsshpnm)
c dsply output 35
c eval *inlr = *on
P*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
P* routine to center text within its own field...
P*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
P Center B
D Center PI 256A OPDESC
D instring 256A Const Options(*varsize)
D* This API is documented in the Integrated Language Enviornment (ILE)
D* CEE API's manual.
D GetStrInf PR ExtProc('CEEGSI')
D ParmNum 10I 0 const
D DataType 10I 0
D CurrLen 10I 0
D MaxLen 10I 0
D dataType S 10I 0
D currLen S 10I 0
D maxLen S 10I 0
D work_str S 256A
D work_rtn S 256A
D work_pad S 10I 0
C* Find out how long instring is...
c callp GetStrInf(1: dataType: currLen: maxLen)
C* Only use the amount that was passed...
c eval work_str = %subst(instring: 1: currLen)
C* how many spaces do we need to pad the string to make it centered?
C ' ' checkr work_str work_pad
c eval(h) work_pad = (currLen - work_pad) / 2
C* pad the string
c eval work_rtn = *blanks
c eval %subst(work_rtn:work_pad+1) = work_str
C* return the result
c return work_rtn
P E
Hope that helps!
"Mark Walter" <mwalter@netrax.net> wrote:
> All,
>
> I have a service program of string handling routines I am trying to
> develop. I have a procedure called "Center" that receives a string
> and an output len then centers the text into a field. I defined the
> parameters as 256 with the CONST and OPTIONS(*varsize) keywords. The
> problem is when i try to pass a sub-element of a data structure to
> the procedure, the entire data structure is passed, not just the
> sub-element. I have included code snippets below.
>
> TIA
>
> Mark Walter
>
> Test program module source
>
> Dshiptods ds 155
> D dsshpnm 35 OVERLAY(shiptods:1)
> D dsship1 35 OVERLAY(shiptods:36)
> D dsship2 35 OVERLAY(shiptods:71)
> D dsship3 35 OVERLAY(shiptods:106)
> D dsshpst 2 OVERLAY(shiptods:141)
> D dsshpzp 10 OVERLAY(shiptods:143)
> D dsshpco 3 OVERLAY(shiptods:153)
> *
> Dlen s 3p 0 INZ(35)
> Doutput s 35
> Dcusno s 8 0 inz(206800)
> Dstore s 8 inz('A1889')
> *
> C EVAL shiptods = GetShipto(cusno:store)
>
> C EVAL output = Center(dsshpnm:len)
> C output DSPLY
> C CLEAR output
>
> String handling service program
>
> HNOMAIN
>
> * module prototypes
>
> DCenter PR 256
>
> D instring 256 OPTIONS(*varsize) CONST
>
> D strlen 3p 0 CONST
>
> * Procedure Interface
>
> PCenter B EXPORT
>
> DCenter PI 256
>
> D instring 256 OPTIONS(*varsize) CONST
>
> D strlen 3p 0 CONST
>
> * work fields
>
> D outstring S 256
>
> Dwork_arr S 1 DIM(256)
>
> Dx S 3 0
>
> Dstrt S 3 0
>
> C MOVEA instring work_arr
>
>
> Instring contains the entire data structure
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