Format: add trailing spaces to character output to left-justify

Question

How do you format a string to have constant width and be left-justified? There is the Aw formatter, where w denotes desired width of chara

Answer 1

To complete @francescalus excellent answer for future reference, the proposed solution also works in case of allocatables in place of string literals:

character(len=:), allocatable :: a_str

a_str = "foobar"

write (*,"(A,I4)") a_str, 42
write (*,"(A,I4)") [character(len=20) :: a_str], 42

will output

foobar  42
foobar                42