Need help with Binary Search algorithm error

Using the g95 compiler, I have an error:

Error: Operands of comparison operator '.EQ.' at (1) are LOGICAL(4)/LOGICAL(4)

I have no idea what this means. I'm includin开发者_运维技巧g the subroutine. Do you have any ideas how to fix this?

Thanks so much for your time.

  SUBROUTINE search(iarray, ItemSought, Found, Location)
CHARACTER(20), DIMENSION(50),INTENT(IN)::itemarray
CHARACTER(20)::ItemSought
LOGICAL, INTENT(OUT)::Found
INTEGER, INTENT(OUT)::Location
INTEGER:: First, Last, Middle

WRITE(*,'(1x,A)',ADVANCE="NO"),"What are you searching for? "
READ*, ItemSought

First=1
Last=SIZE(Iarray)
FOUND = .FALSE.

DO
    IF ((First > Last) .OR. Found) RETURN
        Middle = (First+Last)/2
    IF (ItemSought < Iarray(Middle)) THEN
        Last=Middle-1
    ELSE IF (ItemSought > Iarray(Middle)) THEN
        First=Middle+1
    ELSE
        Found = .TRUE.
        Location = Middle
    END IF
END DO


IF (Found == .TRUE.) THEN
PRINT*, Itemsought

END SUBROUTINE

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I'm not going to admit the last time I used FORTRAN, but it sure looks a lot different than I remember. So this is just a guess.

Based on the error message I'd say it's on this line (you didn't say which):

IF (Found == .TRUE.) THEN

Again just guessing, you usually don't test a logical value by comparing to true/false, you use it directly:

IF (Found) THEN

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The .EQ. (or ==)relational operator, just like .NE. (/=), .LT. (<) and so on, is for comparing numbers only, for comparing logical values you should use .EQV. and .NEQV.