As a programmer everyone knows what is function..!! A function is nothing but a subprogram or a subroutine mainly used for code re usability. In CAL programming we call the code of a function as Trigger code.
Function call is written as same as in C programming-
result := add(a,2);
or
result := add(a+2*3,b);
Pass by value
Change i.e. made in function trigger if it doesn't affect the variables in calling trigger then it 's call by value.
If a change in function trigger affects the variables in calling trigger then it' s call by reference.
You cannot use constants for pass by reference.
actual parameter is used in a calling function trigger.
Formal parameter is used in called function trigger.
5 commonly used built-in functions are:
MESSAGE - Displays message on the screen
STRLEN - returns no. of characters used.
MAXSTRLEN - returns the defined length of the string variable.
COPYSTR - Returns a part or whole of a string.
CLEAR - clears the passed-in variable.
ARRAYLEN - returns the no. of elements in an array.
1. DATA access functions :
GET, FIND, FINDFIRST, FINDLAST, FINDSET, NEXT
GET function-doesn't respect filters, produces run-time error if it fails.
FIND-You can find a value based on specified key value and sorting order.
Avoid using find function as much as possible.
FINDFIRST- to find the first record in a table based on key and filter.
FINDLAST- to find the last record in a table based on key and filter.
FINDSET - to find set of records in a table that corresponds to specified set of filters.
note: In FINDSET you can iterate only from first to last. To iterate from last to first use FIND(+).
Usually, we use this in combination with repeat-until loop.
NEXT - used with FIND and FINDSET to step through records of the table.
2. SORTING AND FILTERING functions :
For key selection,sorting and filtering we use these functions.
SETCURRENTKEY - To select a key for a record.
SETRANGE - sets a simple range ex. to restrict a phone no. to be b/w 8 to 14 numbers we use this.
SETFILTER - It includes in more general way, These filtering includes placeholders, operators, wildcard expressions.
GETRANGEMIN and GETRANGEMAX
retrieve the minimum or maximum value of the filter that is
currently in effect on a field.
4. DATA MANIPULATION functions :
INSERT - inserts a record in a table
MODIFY - changes an existing record
MODIFYALL - performs bulk update of record. Respects filters. It doesn't return values and it doesn't display any errors.
DELETE - to delete a record from the database.
DELETEALL - to delete all records that are selected by the filter settings.
5. Frequently used functions with fields
CALCFIELDS - to calculate flowfields,
if you're accessing record from the code then calcfields must be explicitly specified.
Rec or xRec variable is automatically calculated when a record is retrieved. (no need to call here)
SETAUTOCALCFIELDS - improves performance by reducing no. of round trips to database.
CALCSUMS - calculates total of a column in a table. It respects filters.
note : Maintaining an index for a SumIndexField improves
the performance of CALCSUMS,
but may decrease the performance of insert, modify, and delete operations.
FIELDERROR - stops execution of code causing run-time error. It creates an error message for a field.
FIELDCAPTION - returns caption of a field. We can show the messages very accurately to user by displaying FIELDERROR along with fieldname.
INIT - initializes record by assigning default values.
This function is not applied for primary key.
TESTFIELD - tests if value of field matches the specified value.
VALIDATE - to call OnValidate trigger of a field. It checks the business rules and makes sure that it is not violated by storing invalid value in the field.
6. USER INTERACTION functions:
MESSAGE - displays a text string in a message window.
It's displayed after CAL code finishes execution or when it waits for user interaction.
% - placeholder
\ - new line character
CONFIRM - prompts the user for yes/no option. (to confirm that user wants to continue with the process)
STRMENU - creates a menu window that displays series of options from a comma-delimited string.
ERROR - displays error message and ends the CAL execution. All uncommitted data are rolled back.
7. String Functions:
MAXSTRLEN, STRLEN, STRPOS(case sensitive), COPYSTR, LOWERCASE, UPPERCASE, INCSTR, SELECTSTR(retrieves sub-string from a comma separated string).
8. Date Functions:
DATE2DMY, NORMALDATE, CALCDATE, CLOSINGDATE
9. Numeric functions:
ROUND, ABS, POWER, RANDOM, RANDOMIZE
10. ARRAY functions:
ARRAYLEN,COMPRESSARRAY, COPYARRAY
11. STREAM functions:
CREATEINSTREAM, CREATEOUTSTREAM, READ, READTEXT, WRITE, WRITETEXT, EOS, COPYSTREAM,
12. System functions:
EXIT, CLEAR, CLEARALL, EVALUATE, FORMAT
