Difference between revisions of "Left String"

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[[Category:Sample Code]]
 
[[Category:Service Procedures]]
 
[[Category:Service Procedures]]
 
== Summary ==
 
== Summary ==
 
The following are the RPG/LE fully free-form definitions and instructions needed for using the {{AN}} service procedure.  This service procedure simply allows the caller to extract the left-most '''''n''''' characters from a supplied string.
 
The following are the RPG/LE fully free-form definitions and instructions needed for using the {{AN}} service procedure.  This service procedure simply allows the caller to extract the left-most '''''n''''' characters from a supplied string.
  
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== Justification ==
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By [[User:DaveLClarkI|Dave Clark]]
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Some service procedures (minus their error checking) are so small that one might question creating a service procedure at all.  They might feel that simply employing the stripped-down code directly in their program code is the best way to go (saving the necessity of calling a separate reoutine—with the additional overhead that such action would require).
 
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{| class="wikitable"
 
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|+Rule of Thumb
 
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|-
 
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|Sometimes, having a service procedure is simply a means of making code more self-documenting (i.e., easier for others to understand).
 
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|}
 
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To wit...  Which would you rather see in an RPG program—this?
 
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<pre>
 
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if %subst(myLongString:1:4) = 'TEMP';
 
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// do something
 
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endif;
 
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</pre>
 
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...or, this?
 
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<pre>
 
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if GenUtl_LeftString(myLongString:4) = 'TEMP';
 
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// do something
 
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endif;
 
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</pre>
 
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It is the opinion of many that the second form is more readable and is self-documenting.  Hence, this service procedure.
 
  
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== Service Procedure ==
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== Service Prototype ==
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Place the following in a separate copybook for inclusion in both the caller and the service program source members.
 
<pre>
 
<pre>
 
**free
 
**free
Line 36: Line 19:
 
   PadChar              char(1)  const    options(*nopass);
 
   PadChar              char(1)  const    options(*nopass);
 
end-pr;
 
end-pr;
 +
</pre>
 +
 +
== Service Procedure ==
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Place the following in a service program source member.
 +
<pre>
 +
**free
 +
ctl-opt NoMain AlwNull(*UsrCtl) Debug Option(*SrcStmt:*NoDebugIo)
 +
        DatFmt(*ISO) TimFmt(*ISO);
  
 
//==============================================================================
 
//==============================================================================
Line 70: Line 61:
 
   endif;
 
   endif;
  
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   return NewString;                    // return the suffix string
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   return NewString;                    // return the prefix string
 
end-proc;
 
end-proc;
 
</pre>
 
</pre>
 +
 +
== Examples ==
 +
See the [[Complete]] service procedure.
 +
 +
See the [[Diagnose]] service procedure.
 +
 +
See the [[Escape]] service procedure.
 +
 +
See the [[Inform]] service procedure.

Latest revision as of 17:36, 17 December 2018

Summary

The following are the RPG/LE fully free-form definitions and instructions needed for using the Left String service procedure. This service procedure simply allows the caller to extract the left-most n characters from a supplied string.

By Dave Clark

Service Prototype

Place the following in a separate copybook for inclusion in both the caller and the service program source members. 

**free

//==============================================================================
// Return leftmost number of bytes -- optional padding on right.
//==============================================================================
dcl-pr GenUtl_LeftString          varchar(256) rtnparm;
  OrigString            varchar(65535) const;
  ByteCount             packed(3:0) const;
  PadChar               char(1)   const     options(*nopass);
end-pr;

Service Procedure

Place the following in a service program source member. 

**free
ctl-opt NoMain AlwNull(*UsrCtl) Debug Option(*SrcStmt:*NoDebugIo)
        DatFmt(*ISO) TimFmt(*ISO);

//==============================================================================
// Return leftmost number of bytes -- optional padding on right.
//==============================================================================
dcl-proc GenUtl_LeftString        export;
  dcl-pi *n             varchar(256) rtnparm;
    OrigString          varchar(65535) const;
    ByteCount           packed(3:0) const;
    PadChar             char(1)   const     options(*nopass);
  end-pi;

  dcl-s StrLeng         like(ByteCount);
  dcl-s NewString       varchar(256) inz('');
  dcl-s PadString       char(256) inz(*blanks);

                                       // prevent errors
  StrLeng = ByteCount;                      // start with bytes requested
  if %parms < %parmnum(PadChar)             // if no padding and
  and StrLeng > %len(OrigString);           // request greater than string supplied
    StrLeng = %len(OrigString);             // take supplied string length
  endif;

  if StrLeng > *zero;                  // if something to return
    if StrLeng > %len(PadString);           // if more than what can return
      StrLeng = %len(PadString);            // set to max return length
    endif;
    if %parms < %parmnum(PadChar);          // if no padding
      NewString = %subst(OrigString: 1: StrLeng);
    else;                                   // else, with left padding
      NewString = %subst( OrigString + %xlate(' ': PadChar: PadString)
                        : 1: StrLeng );
    endif;
  endif;

  return NewString;                    // return the prefix string
end-proc;

Examples

See the Complete service procedure.

See the Diagnose service procedure.

See the Escape service procedure.

See the Inform service procedure.

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