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FORTRAN 90+: DECLARATION OF VARIABLE EXAMPLES

There were several examples embedded in the Theory discussion. Here is are other short programs to try:

EXAMPLE 1:

PROGRAM Example1
IMPLICIT NONE
INTEGER :: i 
REAL :: Mach
CHARACTER :: ans

WRITE(*,*) ’DO YOU WISH TO OUTPUT A REAL OR INTEGER VARIABLE?’
WRITE(*,*) ’R = Real; I = Integer’
READ(*,*) ans

IF (ans.eq.’R’) THEN
!  It is good practice to use a decimal even for whole numbers
    Mach= 1.0
    WRITE(*,*) ’Mach number is ’, Mach
ELSE IF (ans.eq.’I’) THEN
!   Notice that no decimal is needed
    i = 1
    WRITE(*,*) ’Integer i is ’, i
ELSE
    WRITE(*,*) ’Your input was not an I or R’
    WRITE(*,*) ’Your input was ’, ans
    STOP
ENDIF
END PROGRAM Example1

EXAMPLE 2:

PROGRAM example2
          IMPLICIT NONE
          CHARACTER(LEN=20) :: interest
          WRITE(*,*) ‘‘Is your interest in Jets,’’ 
                     & ‘‘Rotorcraft, or Spacecraft?’’
          READ(*,*) interest
          SELECT CASE (interest)
               CASE (‘‘Jets’’)
                    WRITE(*,*) ‘‘Work for Boeing’’
               CASE (‘‘Rotorcraft’’)
                    WRITE(*,*) ‘‘Work for Bell’’
               CASE (‘‘Spacecraft’’)
                    WRITE(*,*) ‘‘Work for SpaceX’’
          END SELECT
END PROGRAM