Edit Descriptors

Fortran contains a large number of output edit descriptors which means that very complex I/O patterns can be specified, it is only intended that a summary be presented here. Any good textbook will elaborate:

Where,

• w determines the number of the total number of characters (column width) that the data spans, (on output if there are insufficient columns for the data then numeric data will not (cannot) be printed, CHARACTER data will be truncated).
• d specifies the number of decimal places that the data contains and is contained in the total number of characters. The number will be rounded (not truncated) to the desired accuracy.

and,

• I specifies that the data is of INTEGER type.
• E writes REAL using exponent form, 1.000E+00.
• F uses `decimal point' form, 1.000.
• for F and E the sign is included in the total number of characters, by default plus signs are not output.
• L specifies LOGICAL data. .TRUE. and .FALSE. are output as a single character T or F. If w is greater that one them the single character is padded to the left with blanks.
• A specifies CHARACTER data. If w is specified strings which are too long (more than w characters) will be truncated. If w is not specified any length of string is appropriate.
• X skips the specified number of characters (n blanks are output).

Descriptors or groups of descriptors can be repeated by prefixing or parenthesesing and prefixing with the number of repeats, for example, I4 can be repeated twice by specifying 2I4 and I4,1X can be repeated twice by specifying 2(I4,1X).

Many of the above edit descriptors can be demonstrated:

        WRITE(*,FMT='(2X,2(I4,1X),''name '',A4,F13.5,1X,E13.5)') &
              77778,3,'ABCDEFGHI',14.45,14.5666666

gives

bb****bbbb3bnamebABCDbbbbb14.45000bbb0.14567E+02

where the b signifies a blank! In the above example, the first INTEGER is unable to be written as the number is too long and the last REAL number is rounded to fit into the spaces available. The string is truncated to fit into the space available. A READ statement could use the same format editor.

Type coercion is not performed so INTEGER s cannot be written out as REAL s.

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