Microsoft KB Archive/86927

= FIX: Huge Number in a FORMAT Statement Halts Machine =

Article ID: 86927

Article Last Modified on 12/1/2003

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APPLIES TO


 * Microsoft FORTRAN Compiler 5.0
 * Microsoft FORTRAN Compiler 5.1
 * Microsoft FORTRAN Compiler 5.0
 * Microsoft FORTRAN Compiler 5.1
 * 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 Q86927



SYMPTOMS
Using the Microsoft FORTRAN compiler to compile a program that contains a syntax error in a FORMAT statement can cause the compiler to halt the machine under MS-DOS or to generate a protection violation under OS/2.

With FORTRAN PowerStation, the possible symptoms include:


 * System Hang
 * error F2001: INTEGER value overflow
 * error F2115: syntax error
 * error F2837: label : undefined
 * warning F4989: unexpected character in format



CAUSE
The specific syntax error is caused by a comma at the beginning of a FORMAT statement, followed by a character string constant that contains large integer numbers. The real problem is having a huge number in a FORMAT statement. The out-of-place comma causes the compiler to parse the format as if the first single quotation mark isn't there. Normally, the compiler will determine at the end of the parse that the comma shouldn't be there, and the compiler will issue an error. In this case, however, the machine halts before the error output. Blanks in numbers are ignored. Having a huge number in the format causes the same problem (sample code 2). Because extremely large numbers do not make sense in FORMAT statements, the expected source of the error is the comma, which causes the string to be parsed as a number.



RESOLUTION
Correcting the syntax error eliminates the problem.



STATUS
Microsoft has confirmed this to be a bug in the products listed above. This problem was corrected in Microsoft FORTRAN PowerStation 32, version 4.0.



MORE INFORMATION
The following code can be used to reproduce the problem.

Sample Code 1
open(1,file='data') write(1,10) 10   format(,'110000 115000 120000') ! Causes machine halt end

Sample Code 2
10   format(100000000000000000)  ! Causes machine halt

end This code illustrates the solution.

Sample Code 3
open(1,file='data') write(1,10) 10  format('110000 115000 120000')  ! Correct syntax end

Additional query words: 1.00 5.00 5.10

Keywords: kberrmsg kbfix kblangfortran KB86927

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