Harbour All Functions – E

ELAPTIME()
EMPTY()
EOF()

EOM
EOQ
EOY

ERRORSYS()
EVAL()
EXP()

Exponent 

String Functions

AddASCII

AfterAtNum

AllTrim
Asc

ASCIISum

ASCPos
At

AtAdjust

AtNum
AtRepl
AtToken

BeforAtNum

Chr

CharAdd
CharAnd
CharEven
CharHist
CharList
CharMirr
CharMix
CharNoList
CharNot
CharOdd
CharOne
CharOnly
CharOr
CharPix
CharRela
CharRelRep
CharRem
CharRepl
CharRLL
CharRLR
CharSHL
CharSHR
CharSList
CharSort
CharSub
CharSwap
CharWin
CharXOR

CountLeft
CountRight
Descend
Empty
hb_At
hb_RAt
hb_ValToStr
IsAlpha
IsDigit
IsLower
IsUpper

JustLeft
JustRight

Left
Len
Lower
LTrim

NumAt
NumToken
PadLeft
PadRight

PadC
PadL
PadR

POSALPHA
POSCHAR
POSDEL
POSDIFF
POSEQUAL
POSINS
POSLOWER
POSRANGE
POSREPL
POSUPPER

RangeRem
RangeRepl

RAt

RemAll

RemLeft
RemRight
ReplAll

Replicate

ReplLeft

ReplRight

RestToken

Right
RTrim

SaveToken

SetAtLike
Space
Str

StrDiff

StrFormat

StrSwap

StrTran
StrZero
SubStr

TabExpand
TabPack

Token

TokenAt
TokenEnd
TokenExit
TokenInit
TokenLower
TokenNext
TokenNum
TokenSep
TokenUpper

Transform
Trim
Upper
Val

ValPos
WordOne
WordOnly
WordRem
WordRepl
WordSwap

WordToChar


Len()

LEN()

Returns size of a string or size of an array.

Syntax

      LEN( <cString> | <aArray> ) --> <nLength>

Arguments

<acString> is a character string or the array to check.

Returns

The length of the string or the number of elements that contains an array.

Description

This function returns the string length or the size of an array or the size of a hash table. If it is used with a multidimensional array it returns the size of the first dimension.

Examples

      ? LEN( "Harbour" )           // 7
      ? LEN( { "One", "Two" } )    // 2

Tests

      PROCEDURE Test()
         LOCAL cName := ""
         ACCEPT "Enter your name: " TO cName
         ? LEN( cName )
         RETURN

Compliance

Clipper

Files

Library is rtl

Seealso

EMPTY(), RTRIM(), LTRIM(), AADD(), ASIZE()

C5_EMPTY

 EMPTY()
 Determine if the result of an expression is empty
------------------------------------------------------------------------------
 Syntax

     EMPTY(<exp>) --> lEmpty

 Arguments

     <exp> is an expression of any data type.

 Returns

     EMPTY() returns true (.T.) if the expression results in an empty value;
     otherwise, it returns false (.F.).  The criteria for determining whether
     a value is considered empty depends on the data type of <exp> according
     to the following rules:

     List of Empty Values
     ------------------------------------------------------------------------
     Data Type    Contents
     ------------------------------------------------------------------------
     Array        Zero-length
     Character    Spaces, tabs, CR/LF, or ("")
     Numeric      0
     Date         Null (CTOD(""))
     Logical      False (.F.)
     Memo         Same as character
     NIL          NIL
     ------------------------------------------------------------------------

 Description

     The EMPTY() function has a number of uses.  You can use it to determine
     if a user entered a value into a Get object before committing changes to
     a database file.  It can also determine whether a formal parameter is
     NIL or unsupplied.  In addition, it can test an array for zero-length.

 Notes

     .  Space characters: The EMPTY() function treats carriage
        returns, line feeds, and tabs as space characters and removes these
        as well.

 Examples

     .  These examples illustrate use of EMPTY() against several
        different data types:

        ? EMPTY(SPACE(5)), EMPTY("")        // Result: .T. .T.
        ? EMPTY(0), EMPTY(CTOD(""))         // Result: .T. .T.
        ? EMPTY(.F.), EMPTY(NIL)            // Result: .T. .T.

     .  This example uses EMPTY() to determine whether the user
        entered a value into the first Get object before writing the new
        value to the database file:

        LOCAL cCust := SPACE(15), nAmount := 0
        USE Sales NEW
        @ 10, 10 GET cCust
        @ 11, 10 GET nAmount PICTURE "999.99"
        READ
        //
        IF !EMPTY(cCust)
           APPEND BLANK
           REPLACE Sales->Cust WITH cCust, Sales->Amount ;
              WITH nAmount
        ENDIF

     .  This example uses EMPTY() as part of the VALID clause to force
        the user to enter data into the current Get object:

        LOCAL cCode := SPACE(5)
        @ 2, 5 SAY "Enter code" GET cCode VALID !EMPTY(cCode)
        READ

 Files   Library is CLIPPER.LIB.

See Also: LEN()

 

Hash vs Table

Consider a table for customers records with two character fields : Customer ID and customer name:

Cust_ID Cust_Name
CC001 Pierce Firth
CC002 Stellan Taylor
CC003 Chris Cherry
CC004 Amanda Baranski

 It’s known all possible and necessary operations on a table: APPEND, DELETE, SEEK and so on; by the way, for SEEK we need an index file also.

Listing this table is quite simple:

USE CUSTOMER
WHILE .NOT. EOF()
   ? CUST_ID, CUST_NAME
   DBSKIP()
ENDDO

 If our table is sufficiently small, we can find a customer record without index and SEEK :

LOCATE FOR CUST_ID = “CC003”
? CUST_ID, CUST_NAME

If we want all our data will stand in memory and we could manage it more simple and quick way, we would use an array ( with some considerations about size of table; if it is too big, this method will be problematic ) :

aCustomer := {}    // Declare / define an empty array
USE CUSTOMER
WHILE .NOT. EOF()
   AADD(aCustomer, { CUST_ID, CUST_NAME } )
   DBSKIP()
ENDDO
Traversing this array is quite simple :

FOR nRecord := 1 TO LEN( aCustomer )

    ? aCustomer[ nRecord, 1 ], aCustomer[ nRecord, 2 ]
NEXT
or :

a1Record := {}

FOR EACH a1Record IN aCustomer
   ? a1Record[ 1 ], a1Record[ 2 ]
NEXT

And locating a specific record too:

nRecord := ASCAN( aCustomer, { | a1Record | a1Record[ 1 ] == “CC003” } )

? aCustomer[ nRecord, 1 ], aCustomer[ nRecord, 2 ]

A lot of array functions are ready to use for maintain this array : ADEL(), AADD(), AINS() etc …

Now, let’s see how we could use a hash for achieve this job :

hCustomer := { => } // Declare / define an empty hash

USE CUSTOMER
WHILE .NOT. EOF()
   hCustomer[ CUST_ID ] := CUST_NAME
   DBSKIP()
ENDDO
Let’s traversing :

h1Record := NIL

FOR EACH h1Record IN hCustomer
   ? h1Record: __ENUMKEY(),h1Record:__ENUMVALUE()
NEXT

Now, we have a bit complicate our job; a few field addition to the table :

No: Field Name Type Width  Dec Decription

1

 CUST_ID

C

 5

0

Id ( Code )

2

 CUST_NAME

C

10

0

Name

3

 CUST_SNAM

C

10

0

Surname

4

 CUST_FDAT

D

 8

0

First date

5

 CUST_ACTV

L

 1

0

Is active ?

6

 CUST_BLNCE

N

11

2

Balance

 While <key> part of an element of a hash may be C / D / N / L type; <xValue> part of hash too may be ANY type of data, exactly same as arrays.

So, we can make fields values other than first ( ID) elements of an array:

hCustomer := { => } // Declare / define an empty hash
USE CUSTOMER
WHILE .NOT. EOF()
   a1Data:= { CUST_NAME, CUST_SNAM, CUST_FDAT, CUST_ACTV, CUST_BLNCE }
   hCustomer[ CUST_ID ] := a1Data
   DBSKIP()
ENDDO
Let’s traversing :

h1Record := NIL

FOR EACH h1Record IN hCustomer
   a1Key  := h1Record:__ENUMKEY()
   a1Data := h1Record:__ENUMVALUE()
   ? a1Key
   AEVAL( a1Data, { | x1 | QQOUT( x1 ) } )
NEXT
*-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._
/*
Hash vs Tables
 
*/
#define NTrim( n ) LTRIM( STR( n ) )
#define cLMarj SPACE( 3 )
PROCEDURE Main()

  SET DATE GERM
  SET CENT ON
  SET COLO TO "W/B"
  SetMode( 40, 120 )
 
  CLS
 
  hCustomers := { => } // Declare / define an empty PRIVATE hash
 
  IF MakUseTable() 
 
     Table2Hash()
 
     * Here the hash hCustomers may be altered in any way
 
     ZAP
 
     Hash2Table()
 
  ELSE
      ? "Couldn't make / USE table"
  ENDIF
 
  ?
  @ MAXROW(), 0
  WAIT "EOF HashVsTable.prg"
 
RETURN // HashVsTable.Main()
*-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.
PROCEDURE Table2Hash()
   hCustomers := { => } 
   WHILE .NOT. EOF()
     hCustomers[ CUST_ID ] := CUST_SNAM
     DBSKIP()
   ENDDO
 
   ListHash( hCustomers, "A hash transferred from a table (single value)" )
 
   hCustomers := { => } // Declare / define an empty hash
   DBGOTOP()
   WHILE .NOT. EOF()
      hCustomers[ CUST_ID ] := { CUST_NAME, CUST_SNAM, CUST_FDAT, CUST_ACTV, CUST_BLNCE }
      DBSKIP()
   ENDDO
 
   ListHash( hCustomers, "A hash transferred from a table (multiple values)" )
 
RETURN // Table2Hash()

*-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.

PROCEDURE Hash2Table()
   LOCAL h1Record,;
         c1Key,;
         a1Record,;
         n1Field
 
   FOR EACH h1Record IN hCustomers
      c1Key := h1Record:__ENUMKEY()
      a1Record := h1Record:__ENUMVALUE()
      DBAPPEND()
      FIELDPUT( 1, c1Key )
      AEVAL( a1Record, { | x1, n1 | FIELDPUT( n1 + 1 , x1 ) } )
   NEXT h1Record
   DBGOTOP()
 
   ?
   ? "Data trasferred from hash to table :"
   ?
   WHILE ! EOF()
      ? STR( RECN(), 5), ''
      FOR n1Field := 1 TO FCOUNT()
         ?? FIELDGET( n1Field ), ''
      NEXT n1Field
      DBSKIP()
   ENDDO 
 
RETURN // Hash2Table()

*-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.

PROCEDURE ListHash( hHash, cComment )
 
  LOCAL x1Pair
 
  cComment := IF( HB_ISNIL( cComment ), '', cComment )
 
  ? 
  ? cComment // , "-- Type :", VALTYPE( hHash ), "size:", LEN( hHash )
  ?
  IF HB_ISHASH( hHash ) 
     FOR EACH x1Pair IN hHash
        nIndex := x1Pair:__ENUMINDEX()
        x1Key := x1Pair:__ENUMKEY()
        x1Value := x1Pair:__ENUMVALUE()
        ? cLMarj, NTrim( nIndex ) 
*       ?? '', VALTYPE( x1Pair )
        ?? '', x1Key, "=>"
*       ?? '', VALTYPE( x1Key ) 
*       ?? VALTYPE( x1Value ) 
        IF HB_ISARRAY( x1Value ) 
           AEVAL( x1Value, { | x1 | QQOUT( '', x1 ) } )
        ELSE 
           ?? '', x1Value
        ENDIF 
     NEXT
  ELSE
    ? "Data type error; Expected hash, came", VALTYPE( hHash ) 
  ENDIF HB_ISHASH( hHash )
RETURN // ListHash()
*-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.

FUNCTION MakUseTable() // Make / USE table
 
 LOCAL cTablName := "CUSTOMER.DBF"
 LOCAL lRetval, aStru, aData, a1Record 
 
 IF FILE( cTablName ) 
    USE (cTablName)
 ELSE
    aStru := { { "CUST_ID", "C", 5, 0 },;
               { "CUST_NAME", "C", 10, 0 },;
               { "CUST_SNAM", "C", 10, 0 },;
               { "CUST_FDAT", "D", 8, 0 },;
               { "CUST_ACTV", "L", 1, 0 },;
               { "CUST_BLNCE", "N", 11, 2 } }
    * 
    * 5-th parameter of DBCREATE() is alias - 
    * if not given then WA is open without alias 
    *                              ^^^^^^^^^^^^^ 
    DBCREATE( cTablName, aStru, , .F., "CUSTOMER" ) 
 
    aData := { { "CC001", "Pierce", "Firth", 0d20120131, .T., 150.00 },; 
               { "CC002", "Stellan", "Taylor", 0d20050505, .T., 0.15 },;
               { "CC003", "Chris", "Cherry", 0d19950302, .F., 0 },;
               { "CC004", "Amanda", "Baranski", 0d20011112, .T., 12345.00 } }
 
    FOR EACH a1Record IN aData
        CUSTOMER->(DBAPPEND())
        AEVAL( a1Record, { | x1, nI1 | FIELDPUT( nI1, X1 ) } )
    NEXT a1Record 
    DBGOTOP()
 
 ENDIF 
 
 lRetval := ( ALIAS() == "CUSTOMER" )
 
RETURN lRetval // MakUseTable()

*-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._.-._
 
HashVsTable

Operator overloading

/*
Operator overloading

 Some operators overloaded by extending their functionalities.
"$" was an operator for "checking substring existence in a string" 

 For example :

 ? "A" $ "ABC" // Result: .T.
 ? "Z" $ "ABC" // Result: .F.

 Now, this operator can be used for arrays and hashs too, not only strings.

 See examples below.

 "=>" was a preprocessor operator with meaning "translate to : ...".

Now, this operator can be used as a <key> - <value> separator in Hashs
for define and / or assign <key> - <value> to Hashs.
See examples below.

 "[ ]" was Array element indicator (Special)
 "{ }" was Literal array and code block delimiters (Special)

Now, this indicators can be used for hashs too. 
See examples below.

"+=" is self-increment operator that can be used both numeric 
and string values.

 Such as :

 cTest := "This"
 cTest += " is" 
 ? cTest // This is

 nTest := 3
 nTest += 10
 ? nTest // 13

 Now, this operator can be used for adding elements to an existing hash;
 ( but no for arrays ! ).
 Note : Extended functionalities of $ and += operators depends xHB lib.
        So need this usages to xHB lib and xHB.ch.

 See examples below.

*/
#include "xhb.ch"
PROCEDURE Main()

 CLS

 aFruits := { "apple", "appricot", "cherry", "melon", "pear", "mulberry" }

 ? "aFruits", IF( "pear" $ aFruits, '', 'not ' ) + "contain pear"
 ? "aFruits", IF( "grapes" $ aFruits, '', 'not ' ) +"contain grapes"

 aComplex := ARRAY( 10 )
AEVAL( aComplex, { | x1, i1 | aComplex[ i1 ] := i1 } )

 aComplex[ 5 ] := DATE()
 aComplex[ 7 ] := .F.

 ?
 ? "aComplex", IF( 3 $ aComplex, '', 'not ' ) + "contain 3"
 ? "aComplex", IF( 13 $ aComplex, '', 'not ' ) + "contain 13"
 ? "aComplex", IF( .T. $ aComplex, '', 'not ' ) + "contain .T."
 ? "aComplex", IF( .F. $ aComplex, '', 'not ' ) + "contain .F."
hEmpty := { => }
 ?
 ? "hEmpty is a", VALTYPE( hEmpty ), "type variable have",;
 STR( LEN( hEmpty ), 1 ), "element and it's",;
 IF( EMPTY( hEmpty ), '', 'not' ), "Empty"
hCountries := { 'Argentina' => "Buenos Aires" }
 hCountries += { 'Brasil' => "Brasilia" }
 hCountries += { 'Chile' => "Santiago" }
 hCountries += { 'Mexico' => "Mexico City" }

 ?
 ? "hCountries is a", VALTYPE( hCountries ), "type variable have",;
 STR( LEN( hCountries ), 1 ), "elements and and it's",;
 IF( EMPTY( hCountries ), '', 'not' ), "Empty"
cCountry := NIL
 FOR EACH cCountry IN hCountries
 ? cCountry:__ENUMKEY(), "=>", cCountry:__ENUMVALUE()
 NEXT 

 hDays := { 'Days' => { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" } }

 ?
 ? "hDays", IF( 'Days' $ hDays, '', 'not ' ) + "contain Days" 
 ? "hDays", IF( "Mon" $ hDays, '', 'not ' ) + "contain Mon" 
 ? "hDays['Days']", IF( "Fri" $ hDays["Days"], '', 'not ' ) + "contain Fri"
hLanguages := { "EN" => "English" } +; 
 { "DE" => "Deutsche" } +; 
 { "ES" => "Español" } +; 
 { "FR" => "Français" } +; 
 { "IT" => "Italiano" } +; 
 { "PL" => "Polkski" } +; 
 { "PT" => "Português" } +; 
 { "RU" => "Russkî" } +; 
 { "TR" => "Türkçe" }

 ?
 ? "hLanguages is a", VALTYPE( hLanguages ), "type variable have",;
 STR( LEN( hLanguages ), 1 ), "elements and and it's",;
 IF( EMPTY( hLanguages ), '', 'not' ), "Empty"
cLanguage := NIL 
 FOR EACH cLanguage IN hLanguages
 ? cLanguage:__ENUMKEY(), "=>", cLanguage:__ENUMVALUE()
 NEXT 

 @ MAXROW(), 0 
 WAIT "EOF OprOLoad.prg"
RETURN // OprOLoad.Prg.Main()
OprOLoad

Array and GET tricks

Array and GET tricks