问题
I'm learning Fortran90 after a brief introduction to Fortran77 a few years ago. When printing integers in Fortran, you must specify how many spaces you want to reserve for printing the integer. Consider this program...
implicit none
integer :: i
i = 123
write(*, '(A, I3, A)') "'", i, "'" !3 spaces for output = no padding
write(*, '(A, I5, A)') "'", i, "'" !5 is too many, so output is padded
write(*, '(A, I2, A)') "'", i, "'" !2 is too few, so output is jibberish
write(*, '(A, I:, A)') "'", i, "'" !Default behavior
end program
...which generates the following output.
'123'
' 123'
'**'
' 123'
How do I allocate the correct amount of space for integer printing when I do not know how many digits are in the integer?
Update: If your compiler is F95-compliant, you can use the I0 edit descriptor (i.e., put '(A, I0, A)' for the second argument of the write function in my example above. Thanks @janneb!
回答1:
Use the I0 edit descriptor. Well, to be pedantic IIRC that is Fortran 95, so if you're really strict about no more than F90, then I suppose this won't work.
来源：https://stackoverflow.com/questions/4760600/smart-printing-of-integers-in-fortran90