ASCAN( ) Function
Searches an array for an element containing the same data and data type as an expression.
ASCAN(ArrayName, eExpression [, nStartElement [, nElementsSearched [, nSearchColumn [, nFlags ]]]])
Parameters
ArrayName
Specifies the name of the array to search.eExpression
Specifies the general expression to search for.nStartElement
Specifies the element number at which the search begins. The element number you specify is included in the search. If you omit nStartElement, the entire array is searched by default.nElementsSearched
Specifies the number of elements that are searched. If you omit nStartElement and nElementsSearched, the search begins with the first array element and continues to the last array element if you do not specify nSearchColumn.Note
You can refer to an element in a two-dimensional variable array in one of two ways. The first method uses two subscripts to specify the row and column position of the element in the array; the other method uses an element number. This function and others that manipulate two-dimensional arrays require element numbers (nStartElement and nElementsSearched). Use AELEMENT( ) to return the element number from row and column subscripts in a two-dimensional array.
nSearchColumn
Specifies the array column to search. This is often useful in arrays created by functions such as AFIELDS( ).You can use 0 or a negative number for nSearchColumn to impose a search of the entire array. If you use a value greater than 0 for nSearchColumn, ASCAN( ) treats the specified column as a one-dimensional array, using each data row as an element in the search. For instance, the following example searches only the third and fourth elements of column 2 instead of the entire array.
? ASCAN(abc,"M",3,2,2)Visual FoxPro generates an error if nSearchColumn is a number larger than the number of available columns.
nFlags
Specifies additional search criteria to apply to the scan function. Default scans are case-sensitive.The number you specify in nFlags provides a bit-value that determines the case sensitivity or exactness setting of a scan according to the following table:
NFlag
Bit
Description
0
0000
Behavior existing in Visual FoxPro 6 or earlier
1
0001
Case Insensitive
2
0010
Current behavior existing in the previous version of Visual FoxPro
3
0011
Case Insensitive
4
0100
Exact OFF
5
0101
Case Insensitive; Exact OFF
6
0110
Exact ON
7
0111
Case Insensitive; Exact ON
8
1000
Return row number
9
1001
Case Insensitive; return row number
10
1010
Return row number
11
1011
Case Insensitive; return row number
12
1100
Return row number; Exact OFF
13
1101
Case Insensitive; Return row number; Exact OFF
14
1110
Return row number; Exact ON
15
1111
Case Insensitive; Return row number; Exact ON
The bit values are as follows:
Bit |
Description |
|---|---|
0 |
Case Insensitive bit |
1 |
Exactness ON bit (Only effective if bit 2 is set) |
2 |
Override system Exact setting bit |
3 |
Return row number if 2D array |
nFlags applies only to the ASCAN( ) function and does not affect settings for SET EXACT.
Return Value
Numeric
Remarks
If a match is found, ASCAN( ) returns the number of the element containing the expression. If a match cannot be found, ASCAN( ) returns 0.
The criteria for a successful match of character data are determined by the setting of the system SET EXACT if nFlag with bit 2 is not set. If SET EXACT is ON, an element must match the search expression character for character and have the same length. If SET EXACT is OFF, and an element and search expression match until the end of the expression is reached, the match is successful. For more information on match criteria for character strings, see the string comparison table in the SET EXACT Command topic.
In Visual FoxPro 6.0, the nStartElement and nElementsSearched parameters are optional. The nStartElement must be > 0 while nElementsSearched can be any value. In order to accommodate the nSearchColumn parameter, you will need to bypass these parameters by passing a value of -1.
The nStartElement and nElementsSearched parameters take on special meaning if the value of nSearchColumn is greater than 0. In Visual FoxPro 6.0, they are always referenced to the entire array. Beginning with Visual FoxPro 7.0, if a positive nSearchColumn is passed, the values of nStartElement and nElementsSearched are referenced to the single one-dimensional array represented by the nSearchColumn. For example, the following would only search the third and fourth elements of column 2, and not the entire array:
? ASCAN(abc,"M",3,2,2)
Example
The following example creates and fills an array with company names, and then uses ASCAN( ) to search for a particular company name. If the company name is found, it is removed from the array.
CLOSE DATABASES
OPEN DATABASE (HOME(2) + 'Data\testdata')
USE customer && Open customer table
SELECT company FROM customer ;
WHERE country = 'UK' ;
INTO ARRAY gaCompanies
gnCount = _TALLY
gcName = 'Seven Seas Imports'
CLEAR
DISPLAY MEMORY LIKE gaCompanies*
gnPos = ASCAN(gaCompanies, gcName) && Search for company
IF gnPos != 0
** Company found, remove it from the array ** = ADEL(gaCompanies, gnPos) gnCount = gnCount - 1 ENDIF DISPLAY MEMORY LIKE gaCompanies