Problem with memory allocation for allocatable array( real type )

Question

I am new in Fortran programming so I need a help about allocatable arrays.

This is my simple code:

PROGRAM MY_SIMPLE_CODE

IMPLICIT NONE

INTEGER :: N_TMP, ALLOC_ERR, DEALLOC_ERR

REAL, ALLOCATABLE, DIMENSION(:) :: P_POT

WRITE( *,* ) "ENTER THE VALUE FOR N_TMP:"
 READ( *,* ) N_TMP

IF ( .NOT. ALLOCATED( P_POT) ) ALLOCATE( P_POT( N_TMP), STATUS = ALLOC_ERR )

IF ( ALLOC_ERR .NE. 0 ) STOP( "ERROR - ALLOCATION P_POT !!!")




IF ( ALLOCATED( P_POT) ) DEALLOCATE( P_POT, STATUS = DEALLOC_ERR )

IF ( DEALLOC_ERR .NE. 0 ) STOP( "ERROR - DEALLOCATION P_POT !!!")

END PROGRAM MY_SIMPLE_CODE

When I cobuild this code I got this error message:

Allocate-object is neither a data pointer nor an allocatable variable

What is wrong with this code?

What kind of tricky stuff can be masked in this simple code?

IDE: Code::Blocks TDM_GCC_5 1 0

OS: Win 10 X64

I don't know about Code::Blocks, but I noticed that you use the STATUS= term in your allocation and deallocation. That's wrong, the keyword is STAT=. — chw21
– chw21, Commented Mar 6, 2019 at 23:59
It's probably what chw21 said, but why don't you post the error message for us to see? — Monochromatic
– Monochromatic, Commented Mar 7, 2019 at 0:18
@Monochromatic The question is now complete because I added error message. — user10930250
– user10930250, Commented Mar 7, 2019 at 0:37
You have two errors in your code. First, as pointed out by @chw21, you want to STAT= instead of STATUS. The error is correctly pointing at STATUS. gfortran assumed if is a variable name. Second, the STOP does not use parathesis. Remove those. — Steve
– Steve, Commented Mar 7, 2019 at 0:49
@Steve I did not got warning from compiler that parathesis are syntax error. Why? Can I get a explanation because I want to know reason for that. — user10930250
– user10930250, Commented Mar 7, 2019 at 11:00

Rodrigo Rodrigues · Accepted Answer · 2019-03-08 08:18:41Z

1

Just like @Steve said in the comment, the keyword for the status of allocation/deallocation is STAT, not STATUS. The error comes because the compiler doesn't recognize the name and thinks it is a variable.

Moreover, there is a syntax error because there must be at least a space between the STOP statement and the opening brace (or no braces at all).

IF ( .NOT. ALLOCATED( P_POT) ) ALLOCATE( P_POT( N_TMP), STAT = ALLOC_ERR )
IF ( ALLOC_ERR .NE. 0 ) STOP "ERROR - ALLOCATION P_POT !!!"
!(...)
IF ( ALLOCATED( P_POT) ) DEALLOCATE( P_POT, STAT = DEALLOC_ERR )
IF ( DEALLOC_ERR .NE. 0 ) STOP "ERROR - DEALLOCATION P_POT !!!"

edited Mar 8, 2019 at 8:18

answered Mar 7, 2019 at 7:57

Rodrigo Rodrigues

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3 Comments

francescalus Over a year ago

It's not so much that STOP ("x") isn't allowed and must be written as STOP "x", but that STOP( "x" ) isn't allowed. The first is valid, the last isn't (placing of spaces).

Rodrigo Rodrigues Over a year ago

This is weird... Fortran is not spaces-sensitive in general, specially with braces.

francescalus Over a year ago

Not very weird: it's no different (in free form) from having to write real x rather than realx or 100 continue rather than 100continue, etc. if(x) is allowed whereas stop(x) isn't, and the difference is that in the latter case the ( is an integral part of the constant (x) - much as you can't have stop1 instead of stop 1.

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