Microsoft KB Archive/109874

= FIX: Constants Out of Range Not Found by /4Yb =

Article ID: 109874

Article Last Modified on 10/17/2003

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APPLIES TO


 * Microsoft FORTRAN PowerStation 1.0 Standard Edition
 * Microsoft Fortran PowerStation 1.0a for MS-DOS
 * Microsoft FORTRAN PowerStation 32

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This article was previously published under Q109874



SYMPTOMS
A program that contains a simple arithmetic expression including constant out of range may produce incorrect results. Using the -4Yb compiler option does not give a run-time error on constants that are out of range even though it should.



CAUSE
The constant folding algorithm (arithmetic performed at compile time) generates 0 (zero) for the variable out of range.



RESOLUTION
Avoid using a simple constant expression that might be out of range. Use the temporary variable for the intermediate results and then use this variable in the expression. Compile the program with -4Yb and the appropriate run-time error will be generated.



STATUS
Microsoft has confirmed this to be a problem in Microsoft FORTRAN PowerStation 32 for NT, version 1.0 and FORTRAN Powerstation for MS-DOS version 1.0 and 1.0a. This is not a problem in Microsoft FORTRAN for MS-DOS, version 5.1, or FORTRAN PowerStation 32, version 4.0.



Sample Code #1
c Compile options required: -4Yb does not affect the behavior c The following code reproduces the problem.

i=2**50 write (*,*) i      end

Sample Code #2
c Compile options required: -4Yb c The following code solves the problem and generates the following c run-time error: run-time F6099: $DEBUG c           -INTEGER arithmetic overflow

j=50 i=2**j write (*,*) i      end

Additional query words: 1.00 runtime run time

Keywords: kbbug kbfix kbcompiler KB109874

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