What are write parameters?
Description
Write parameters are used, with the
write and
writeln procedures, to specify the values that
these procedures should write to files.
Writing To Non-Text Files
If the file being written to is not a text file (i.e. not a file
associated with a file variable of
type text) then the write parameters are
just expressions, and the values of these
expressions are written without conversion to the file.
Writing To Text Files
If the file being written to is a text file (i.e. a file associated with a
file variable of type text)
then the write parameters can be made up of the following three items:
- An expression specifying the value to be written to
the file. NOTE: Non-string values are converted to string values before being
written to the file, however the type of the write parameter is the type
of the value before it was converted.
- An optional expression of
integral type that specifies the minimum width of the
string value written to the file. If this item is not supplied then the minimum width
used depends on the type of the write parameter as follows:
If the write parameter has an
integral type or
boolean type then the default minimum width is eigth (8).
If the write parameter is of real type
then the default minimum width is nine (9).
If the write parameter is of string type
then the default minimum width is the length of the string.
If the write parameter is of
If the write parameter is of any other type then the default minimum width is
one (1).
- An optional expression of
integral type that specifies the number of digits that
follow the decimal point in the converted string (the value is converted into a fixed point
representation). If this item is not supplied, and a value of
real type is being converted, then the value is converted
into an exponential representation. NOTE: This item only be used when the
write parameter is of real type.
If the string value being written to the text file is shorter than the minimum width then it is
padded with spaces on the left until it is the same length as the minimum width. If the string
value being written to the file is longer than the minimum width then the entire string value
is written to the file unless the write parameter is of
string type or of
boolean type in which case the string value is truncated
on the right to the same length as the minimum width.
