Fortran Modern alternatives to historical features Assigned format specifiers
Example
Before Fortran 95 it was possible to use assigned formats for input or output. Consider
integer i, fmt
read *, i
assign 100 to fmt
if (i<100000) assign 200 to fmt
print fmt, i
100 format ("This is a big number", I10)
200 format ("This is a small number", I6)
end
The assign statement assigns a statement label to an integer variable. This integer variable is later used as the format specifier in the print statement.
Such format specifier assignment was deleted in Fortran 95. Instead, more modern code can use some other form of execution flow control
integer i
read *, i
if (i<100000) then
print 100, i
else
print 200, i
end if
100 format ("This is a big number", I10)
200 format ("This is a small number", I6)
end
or a character variable may be used as the format specifier
character(29), target :: big_fmt='("This is a big number", I10)'
character(30), target :: small_fmt='("This is a small number", I6)'
character(:), pointer :: fmt
integer i
read *, i
fmt=>big_fmt
if (i<100000) fmt=>small_fmt
print fmt, i
end
