1. 21 April, 2000 CS1001 Lecture 27 Final Examination Review

2. 21 April, 2000 From Before the Midterm Basic Program Elements Declaration of Variables Declaration of Parameters Initialization of Variables Logical Operators Selective Execution CASE Statements Repetitive Execution How to Prompt for an Input

3. 21 April, 2000 Basic Program Elements Every program must have: –PROGRAM ProgramName –IMPLICIT NONE –END PROGRAM ProgramName Declaration of Variables REAL :: rVar1, rVar2 INTEGER :: iVar1, iVar2 CHARACTER(LEN) :: cVar1, cVar2*LEN LOGICAL ::bVar

4. 21 April, 2000 Declaration of Parameters REAL, PARAMETER :: rCONS = 3.14159 INTEGER, PARAMETER :: iCONS = 5240 Initialization of Variables rVar1 = 1.23 iVar2 = 2240 cVar3 = “Hello world” bVar4 =.TRUE.

5. 21 April, 2000 Relational Operators = /= <= >= < >.EQ..NE..LE..GE..LT..GT. Logical Operators.NOT..AND..OR..EQV..NEQV. Negation Conjunction Disjunction Equivalence Nonequivalence

6. 21 April, 2000 Selective Execution Normal IF Structure Simple IF Structure Normal IF Structure IF (log_exp1.AND. log_exp2) THEN statements to be performed ELSE IF (log_ex3.OR. log_ex4) THEN statements to be performed ELSE statements to be performed END IF

7. 21 April, 2000 Simple IF Statement IF (logical_expression) stmt e.g., IF (logical_expression) EXIT Used to get out of an infinite DO loop Equivalent to: IF (logical_expression) THEN EXIT END IF

8. 21 April, 2000 CASE Constructs SELECT CASE (iItem) CASE (:0) statements to perform if iItem <= 0 CASE (1) statements to perform if iItem = 1 CASE (2:5) statements to perform if iItem is 2-5 CASE (9:) statements to perform if iItem >= 9 CASE DEFAULT statements to perform for other values END SELECT

9. 21 April, 2000 Repetitive Execution Counter-controlled loops perform an operation a given number of times DO-EXIT or while or until loops perform an operation until a condition becomes true that causes the loop to end Counter-Controlled DO iLoop = init_val, final_val, step_size statements to be performed END DO

10. 21 April, 2000 DO-EXIT (While) Loop DO statements to be performed IF (logical expression) EXIT statements to be performed END DO

11. 21 April, 2000 Prompting for Input PRINT *, “Enter an integer from 1 to 9: ” READ *, iInput PRINT *, “Enter a value 0.0 or greater: ” READ *, rInput PRINT *, “Enter Q to quit: ” READ *, cInput

12. 21 April, 2000 Stuff Since the Midterm More Basic Program Elements Subprograms - Subroutines, Functions Structures One-Dimension Arrays Implied DO Loops Multi-Dimension Arrays Formatted Output Text Processing Internal Files How to Create a File How to Read from a File

13. 21 April, 2000 More Basic Program Elements Programs containing subprograms must contain the following: PROGRAM MyProgram : CONTAINS subprograms go here (internal) : END PROGRAM MyProgram subprograms go here (external)

14. 21 April, 2000 Internal Subroutines Invoked with a CALL Statement CALL MySubRoutine(iArg, rArg) Defined after CONTAINS statement SUBROUTINE MySubRoutine(iArg, rArg) INTEGER, INTENT(IN) :: iArg REAL, INTENT(OUT) :: rArg INTEGER :: iLocalVariable REAL :: rLocalVariable statements to be performed END SUBROUTINE MySubRoutine

15. 21 April, 2000 External Subroutines Invoked with a CALL Statement CALL MySubRoutine(iArg, rArg) Defined after END PROGRAM statement SUBROUTINE MySubRoutine(iArg, rArg) INTEGER, INTENT(IN) :: iArg REAL, INTENT(OUT) :: rArg INTEGER :: iLocalVariable REAL :: rLocalVariable statements to be performed END SUBROUTINE MySubRoutine

16. 21 April, 2000 Internal Functions Invoked with an equation or statement rValue = rMyFunction(iValue) Defined after the CONTAINS statement FUNCTION rMyFunction(iValue) REAL :: rMyFunction INTEGER, INTENT(IN) :: iValue statements to be performed rMyFunction = some value to return END FUNCTION rMyFunction

17. 21 April, 2000 External Functions Invoked with an equation or statement rValue = rMyFunction(iValue) Declared as EXTERNAL REAL, EXTERNAL :: rMyFunction Defined after the END PROGRAM statement FUNCTION rMyFunction(iValue) REAL :: rMyFunction INTEGER, INTENT(IN) :: iValue statements to be performed rMyFunction = some value to return END FUNCTION rMyFunction

18. 21 April, 2000 Structures (not in exam) Declare a structure TYPE sVariable REAL :: rVar1, rVar2 INTEGER :: iVar1, iVar2 END TYPE sVariable Declare an instance of the structure TYPE(sVariable) :: sInstance Reference the variables in it iItem = sInstance%iVar1 rPrice = sInstance%rVar2

19. 21 April, 2000 One-Dimension Array Declare and dimension INTEGER, DIMENSION(1:9) :: iVar1, iVar2 REAL, DIMENSION(0:25) :: rVar1, rVar2 Initialize whole array iVar1 = 0 iVar2 = (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /) rVar1 = 9.99 rVar2 = (/1.0, 1.1, 1.2, 1.3, …, 1.25 /) Reference elements using subscript iVar(8) = 25 rVar(19) = 17.49

20. 21 April, 2000 Multi-Dimension Array Declare and dimension INTEGER,DIMENSION(1:9,1:3):: iVar1, iVar2 REAL, DIMENSION(0:25,1:5) :: rVar1, rVar2 Initialize whole array iVar1 = 0 rVar1 = 9.99 Reference elements using subscript iVar(8,2) = 25 rVar(19,5) = 17.49

21. 21 April, 2000 Formatted Output PRINT 20, iVar, rVar, cVar 20 FORMAT(1X, I2.2, 5X, F8.3, T20, A) 1X, 5X - horizontal spaces I2.2 - Integer, width of 2, minimum 2 digits F8.3 - Real, width of 8 (including sign and decimal point), with 3 decimal places T20 - Tab to absolute column position - column 20 A - Alphabetic string

22. 21 April, 2000 Creating a File The file is opened as a new file for writing OPEN(UNIT=12, FILE=“input.dat”, “NEW”, “WRITE”) Formatted data is written to the file WRITE(12,40) iVar, rVar, cVar 40 FORMAT(1X, I5, F8.3, A25) The file is closed CLOSE(12)

23. 21 April, 2000 Reading from a File The file is opened as an old file for read OPEN(UNIT=13, FILE=“input.dat”, “OLD”, “READ”) Formatted data is read from the file READ(13,40,IOSTAT=EOF) iVar, rVar, cVar 40 FORMAT(1X, I5, F8.3, A25) The file is closed –CLOSE(13)

24. 21 April, 2000 Internal Files Used to convert character form to integer given cDate = “November 25,1997” then cYear = cDate(14:17) and READ (UNIT = cYear, FMT = ‘(I4)’) iYear Assigns the integer value 1997 to integer variable iYear

25. 21 April, 2000 Text Processing Getting the length of a string Var = LEN(String) Var = LEN(“Hello, my name is”) => 17 Finding text within a string Found = INDEX(String, Text) Found = INDEX(“IMAGINE”, “IN”) => 5

26. 21 April, 2000 Implied DO Loops Used to read data into an array READ (10, *) (iInArr(I), I=1, iLastNum) Equivalent to DO I = 1, iLastNum READ (10, *) iInArr(I) END DO