On input, an edit descriptor such as Fw.d specifies that w characters (the field width) are to be read from the external field.
If the field contains fewer than w characters, the input
statement will read characters from the next data field in the
record. You can prevent this by padding the short field with blanks
or zeros, or by using commas to separate the
input data.
You can use the OPEN statement specifier PAD='YES'
to indicate blank padding for short fields of
input data. However, blanks can be interpreted as blanks or
zeros, depending on which default behavior is in effect at the time.
Consider the following:
If 3 is input for J, the value of J will be 30000 or 3 depending on
which default behavior is in effect (BLANK='NULL' or BLANK='ZERO').
This can give unexpected results.
To ensure that the desired behavior is in effect, explicitly specify
the BN or BZ edit descriptor. For example, the following ensures
that blanks are interpreted as blanks (and not as zeros):
Using Commas to Separate Input Data
You can use a comma to terminate a short data field. The comma
has no effect on the d part (the number of characters
to the right of the decimal point) of the specification.
The comma overrides the w specified for the I, B, O, Z, F,
E, D, EN, ES, G, and L edit descriptors. For example, suppose the
following statements are executed:
Suppose a record containing the following values is read:
The following assignments occur:
A comma can only terminate fields less than w characters
long. If a comma follows a field of w or more characters,
the comma is considered part of the next field.
A null (zero-length) field is designated by two successive commas,
or by a comma after a field of w characters. Depending on
the field descriptor specified, the resulting value assigned is 0,
0.0, 0.D0, or .FALSE.
For details on input processing, see Section 11.2.2.
READ (*, '(I5)') J
READ (*, '(BN, I5)') J
READ (5,100) I,J,A,B
100 FORMAT (2I6,2F10.2)
1, -2, 1.0, 35
I = 1
J = -2
A = 1.0
B = 0.35
Previous Page Next Page Table of Contents