Error With REAL Statement In Fortran [closed] - fortran

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I have a program that gets a Matrix of Celsius Temperature and Prints The Minimum, Maximum, Averange and Variance of Those Temperatures On The Screen. This Is The Code:
PROGRAM MATRIS
IMPLICIT NONE
INTEGER::M,N,I,J
REAL::AVG,VAR,LEAST,LARGEST,SUM,MIN_A,MAX_A
REAL,DIMENSION(:,:),ALLOCATABLE::A,B
PRINT*,"PLEASE ENTER column,raw"
READ*,M,N
ALLOCATE(A(M,N),B(M,N))
OPEN(10,FILE="C:/TEMP.txt",STATUS="OLD",ACTION="READ")
OPEN(10,FILE="C:/output.txt",STATUS="REPLACE",ACTION="WRITE")
OPEN(10,FILE="C:/output_statistic",STATUS="REPLACE",ACTION="WRITE")
READ*,(10,*)((A(I,J),I=1,M),J=1,N)
DO J=1,N
DO I=1,M
B(I,J)=A(I,J)+273.15
END DO
END DO
WRITE(20,'(2(F6.2,2X))')((A(I,J),I=1,M),J=1,N)
REAL::R1,R2,R3,R4,R5
PRINT*,"PLEASE ENTER YOUR NUMBER"
READ*,R1,R2,R3,R4,R5
CALL REVERSE(R1,R2,R3,R4,R5)
PRINT*,R2,R3,R4,R5
CONTAINS
SUBROUTINE REVERSE(A,D,E,F,G)
IMPLICIT NONE
REAL,INTENT(IN)::A
REAL,INTENT(OUT)::D,E,F,G
SUM=0.
VAR=0.
LARGEST=0.
LEAST=10000.
DO I=1,N
READ*,A
SUM=SUM+A
MAX_A=MAX(LARGEST,A)
LARGEST=MAX_A
MIN_A=MIN(LEAST,A)
LEAST=MIN_A
VAR=SQRT(VAR+(A-AVG)**2)
AVG=SUM/N
D=MAX_A
E=MIN_A
F=VAR
G=AVG
END DO
RETURN
PRINT*,D/E/F/G
END SUBROUTINE REVERSE
END PROGRAM MATRIS
At Line 19 I get this error:
REAL cannot appear after executable statements
And Line 34 I get this Error:
A appears on the left hand side of an assignment yet has the INTENT(IN) attribute
How Can I fix These. And Can You See If There Are Other Errors In My Program? I'm new in Fortran And I need your help. Thanks

Answer 1

You have to declare all your variables at the beginning of a program or subroutine.
You will have to move your
REAL::R1,R2,R3,R4,R5
up to where you declare the other variables.
As for the second question: You have declared A to be INTENT(IN) in your subroutine. That means that the subroutine can't change its value.
But the READ*,A would do just that. So the compiler tells you that this is inconsistent and can't be compiled.
But please, do me and yourself a favour and get a good book about Fortran programming. Or do some online Fortran courses, if you find some.
There are many more errors in your code, and if you try to plough ahead this way, your code will never do what you want it to do.