Advanced Repetition Structure and String Functions (Unit 10)

1. Advanced Repetition Structure and String Functions(Unit 10) Visual Basic for Applications

2. Objectives • In this unit, you will learn how to: • Perform repetition using the Do…Loop statement • Manipulate a string using string functions • Search for a string within another string • Sort a table in Word using the Sort method

3. Concept Lesson:More on Repetition Structure • You also can use the repetition structure to repeat one or more instructions until some condition is met • You can use the VBA Do…Loop statement to code that type of repetition structure

4. The Do…Loop Statement • You can use the VBA Do…Loop statement to code a repetition structure that repeats its instructions either while some condition is true or until some condition becomes true • VBA also has another version of the Do…Loop statement, where the {While|Until} appears in the Loop clause rather than in the Do clause • The Do…Loop statement begins with the Do clause and it ends with the Loop clause • The {While | Until} indicates that you can select only one of the keywords appearing within the braces

5. Syntax and Examples of the Do…Loop Statement Exhibit 10-1: The syntax and examples of the Do…Loop statement

6. The VBA StringManipulation Functions • VBA provides a set of functions that makes string manipulation an easy task • In this lesson, you will learn how to use four of the most frequently used string manipulation functions: • Left • Right • Mid • Instr

8. The Left and Right Functions • The Left and Right functions return oneor more characters from a string, starting at either the left or right end of the string Exhibit 10-2: The syntax and examples showing the Left and Right functions

9. The Mid Function • The Mid function, which has the syntax Mid(String:=string, Start:=start[,Length:= length]), returns length number of characters from the string, beginning with the start character Exhibit 10-3: The syntax and examples of the Mid function

10. The Instr Function • You can use the Instr function to search a string to determine ifit contains another string • The syntax of the Instr function is Instr(start, string1, string2 [, compare]) Exhibit 10-4: The syntax and examples of the Instr function

11. Summary To use the Do…Loop statement to code the repetition structure: • Use the syntax shown in Exhibit 10-1, where condition, which must evaluate to either True or False, can contain variables, constants, functions, mathematical operators, comparison operators, and logical operators To return characters from a string: • Use the Left, Right, or Mid functions • The Left function, the syntax of which is Left(String:=string, Length:=length), returnsthe left-most length number of characters from the string

12. Summary To return characters from a string: • The Right function, the syntax of which is Right(String:=string, Length:=length), returns the right-most length number of characters from the string • The Mid function, the syntax of which is Mid(String:=string, Start:=start[, Length:=length]), returns length number of characters from the string, beginning at position start

13. Summary To search a string if it contains another string: • Use the Instr function, the syntax of which is Instr(start, string1, string2[, compare]). The Instr function does not support the use of named arguments • Start is a numeric expression that sets the starting position for the search • If string2 is contained within string1, thenthe Instr function returns the starting position of string2

14. Excel Lesson: Viewing the Consultants Worksheet and the BreakNameApart Procedure • Before creating the macro that will separate each consultant’s full name into his or her first and last name, view the workbook, and the code template for the BreakNameApart procedure

15. Pseudocode for the BreakNameApart Procedure Exhibit 10-5: The pseudocode for the BreakNameApart procedure

16. Viewing the Consultants Worksheet and the BreakNameApart Procedure • The BreakNameApart procedure will use the intLocation variable to store the value returned by the Instr function, and it will use the shtConsult variable to store the address of the Consultants worksheet

17. Word Lesson:Viewing the Guest Document • Before creating the procedure that will sort the list and then remove any duplicate names, view the document and the code template for the SortAndRemoveDuplicates procedure

18. Sorting a Table • You can use the Table object’s Sort method to sort the entries in a table in either ascending or descending order • The Sort method’s ExcludeHeader argument, which can be set to either the Boolean value True or the Boolean value False, controls whether the first row in the table is sorted along with the remaining table rows • You can sort the table entries based on the values stored in one, two, or three different columns

19. Sorting a Table • You use the SortFieldType, SortFieldType2, and SortFieldType3 arguments to indicate the type of data contained in the FieldNumber, FieldNumber2, and FieldNumber3 columns, respectively Exhibit 10-6: The syntax and examples of the Table object’s Sort method

20. Pseudocode for the SortAndRemoveDuplicates Procedure Exhibit 10-7: The pseudocode for the SortAndRemoveDuplicates procedure

21. Coding the SortAndRemoveDuplicates Procedure • The SortAndRemoveDuplicates procedure will use the intRow variable in a Do…Loop statement that repeats its instructions for each table row that contains guest information • This procedure will use the strCurrentName and strPreviousName variables to store the names entered in the current and previous rows, respectively, in the table

22. Access Lesson:Viewing the Database and the LocateInstructor Procedure • Before creating the macro that will display the names of instructors teaching a particular course, you will view the records contained in the database’s AdjunctFaculty table

23. Pseudocode for the LocateInstructor Procedure Exhibit 10-8: The pseudocode for the LocateInstructor procedure

24. Viewing the Database and the LocateInstructor Procedure • This procedure will use the String variable strCourseNum to store the course number entered by the user • It will use the String variable strFoundto store the letter “Y”, indicating that the procedure located at least one instructor who teaches the course

25. Viewing the Database and the LocateInstructor Procedure • The cnnAdjFac and rstAdjFac object variables will be used to store the addresses of the Connection and Recordset objects, respectively

26. Viewing the Database and the LocateInstructor Procedure • You will use the Do…Loop statement along with the Recordset object’s EOF property to code the appropriate loop • The Recordset object’s EOF property returns the Boolean value True if the record pointer, which Access uses to keep track of the current record, is positioned after the last record in the recordset • Because a Recordset is an object rather than a collection, you cannot use the For Each…Next statement that you learned about in unit 9 to code the loop; however, you can use the For…Next statement