Using Backslashes with the SYSTEM and SPAWN Functions (59603)


The information in this article applies to:

  • Microsoft FORTRAN Compiler for MS-DOS 4.0
  • Microsoft FORTRAN Compiler for MS-DOS 4.01
  • Microsoft FORTRAN Compiler for MS-DOS 4.1
  • Microsoft FORTRAN Compiler for MS-DOS 5.0
  • Microsoft FORTRAN Compiler for MS-DOS 5.1
  • Microsoft FORTRAN compiler for OS/2 4.1
  • Microsoft FORTRAN compiler for OS/2 5.0
  • Microsoft FORTRAN compiler for OS/2 5.1
  • Microsoft FORTRAN PowerStation for MS-DOS 1.0
  • Microsoft FORTRAN PowerStation for MS-DOS 1.0a
  • Microsoft Fortran Powerstation 32 for Windows NT 1.0
  • Microsoft Fortran Powerstation 32 for Windows NT 4.0
This article was previously published under Q59603

SUMMARY

Care should be taken when using backslash (\) characters in strings passed to the SYSTEM and SPAWN functions. The SYSTEM and SPAWN functions are actually C routines. In C, the backslash character is used to denote an editing descriptor, somewhat similar to the way the I, F, X, etc., editing descriptors are used in the FORTRAN FORMAT statement. The following sample SYSTEM call incorrectly uses the backslash character: 
   I = SYSTEM('dir c:\temp'C)
No compile warnings are given, but a run-time error is produced because \t is interpreted as an editing descriptor.

NOTE: Under Fortran PowerStation 4.0, a compiler warning is generated for the line above. The warning message is:
warning FOR4552: unrecognized character escape sequences in C-string
The C function associated with the FORTRAN SYSTEM function will interpret the backslashes as editing descriptors. In C, if you want to print out a backslash you must follow the first backslash with another; this tells C to temporarily ignore the backslash as an editing descriptor. The following line demonstrates how to properly use the backslash character in the SYSTEM and SPAWN functions: 
   I = SYSTEM('dir c:\\temp'C)
NOTE: In FORTRAN PowerStation, SYSTEMQQ is equivalent to SYSTEM.
Modification Type:MajorLast Reviewed:12/1/2003
Keywords:kbLangFortran KB59603
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