Language Reference

Editing

Editing is performed on fields. A field is the part of a record that is read on input or written on output when format control processes one of the data or character string edit descriptors. The field width is the size of the field in characters.

The I, F, E, EN, ES, B, O, Z, D, G, and extended precision Q edit descriptors are collectively called numeric edit descriptors. They are used to format integer, real, and complex data. The following general rules apply to these edit descriptors:

• On input:
  • Leading blanks are not significant. The interpretation of other blanks is controlled by the BLANK= specifier in the OPEN statement and the BN and BZ edit descriptors. A field of all blanks is considered to be zero. Plus signs are optional, although they cannot be specified for the B, O, and Z edit descriptors.
  • In F, E, EN, ES, D, G, and extended precision Q editing, a decimal point appearing in the input field overrides the portion of an edit descriptor that specifies the decimal point location. The field can have more digits than can be represented internally.
• On output:
  • Characters are right-justified inside the field. Leading blanks are supplied if the editing process produces fewer characters than the field width. If the number of characters is greater than the field width, or if an exponent exceeds its specified length, the entire field is filled with asterisks.
  • A negative value is prefixed with a minus sign. By default, a positive or zero value is unsigned; it can be prefixed with a plus sign, as controlled by the S, SP, and SS edit descriptors.

    +---------------------------------Fortran 95---------------------------------+

    
    
  • Depending on whether you specify the signedzero or nosignedzero suboptions for the -qxlf90 compiler option the following will result for the E, D, Q(Extended Precision), F, EN, ES or G(General Editing) edit descriptors:
    • when the signedzero suboption is chosen, and the internal value is negative or a negative zero on output, a minus sign always be written out to the output field, even if the output value is zero. The Fortran 95 standard requires this behavior.

      +-------------------------------IBM Extension--------------------------------+

      
      

      Note that in XL Fortran, a REAL(16) internal value of zero is never treated as a negative zero.

      +----------------------------End of IBM Extension----------------------------+

    • when the nosignedzero suboption is chosen, and the output value is zero, no minus sign will be written out to the output field, even if the internal value was negative. The Fortran 90 standard requires this behavior, and is consistent with the behavior of XL Fortran Version 5.1.1.

    +----------------------------End of IBM Extension----------------------------+

    +-------------------------------IBM Extension--------------------------------+

    
    
  • In XL Fortran, a NaN (not a number) is indicated by "NaNQ", "+NaNQ", "-NaNQ", "NaNS", "+NaNS", or "-NaNS". Infinity is indicated by "INF", "+INF", or "-INF".

    +----------------------------End of IBM Extension----------------------------+

  Notes:

  1. The ES and EN edit descriptors will behave the same for both the signedzero and nosignedzero suboptions when the internal value is non-zero. That is, the minus sign will be printed out whenever the value is negative.

  2. In the examples of edit descriptors, a lowercase b in the Output column indicates that a blank appears at that position.

Complex Editing

A complex value is a pair of separate real components. Therefore, complex editing is specified by a pair of edit descriptors. The first one edits the real part of the number, and the second one edits the imaginary part of the number. The two edit descriptors can be the same or different. One or more control edit descriptors can be placed between them, but not data edit descriptors.