Posted: Wed Feb 21, 2007 4:06 pm Post subject: Function returning string - cannot write result
Hello,
I have a problem trying to WRITE the result of a function that returns a string. Whenever I try to WRITE the result, I get an error: "PGFIO-F-235/formatted write/internal file/edit descriptor does not match item." However, if I try PRINT, the result is displayed correctly.
Code:
PROGRAM test
CHARACTER(LEN=4) :: mambo !function
INTEGER :: x
x = 1
WRITE(*, '(A)') mambo (x)
END PROGRAM test
FUNCTION mambo (x) RESULT (string)
CHARACTER(LEN=4) :: string
INTEGER :: x
WRITE(string, "(I4.4)") x
RETURN
END FUNCTION mambo
Since x = 1, I would expect the program to print out '0001'. Instead, I get:
Code:
inferno [1739] ./a.out
PGFIO-F-235/formatted write/internal file/edit descriptor does not match item
If I replace "WRITE(*, '(A)') mambo (x)" with "PRINT *, mambo(x)" ... it works as expected.
Joined: 30 Jun 2004 Posts: 2033 Location: The Portland Group Inc.
Posted: Wed Feb 21, 2007 5:45 pm Post subject:
Hi mwhite,
The statement "WRITE(*, '(A)') mambo (x)" is illegal F95 since mambo contains an WRITE statement. Functions that are part of an output list may not cause execution of another input/output statement. You'll need to create a temporary variable to hold the return value. I believe this restriction has been lifted in the F2003 standard.
- Mat
Example:
Code:
% cat mambo.f90
PROGRAM test
INTEGER :: x
character(len=4) :: temp
character(len=4) :: mambo
x = 1
temp = mambo(x)
WRITE(*, '(A)') temp
END PROGRAM test
FUNCTION mambo (x) result(string)
CHARACTER(LEN=4) :: string
INTEGER :: x
WRITE(string, '(I4.4)') x
RETURN
END FUNCTION mambo
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