Fortran: remove characters from a string

How do I remove characters from a string?

For example, I have a string called 'year', which I want to change from 4 characters to 2 chracters. It is defined like so:

character(4) :: year = "2011"

How do I truncate the string to 2 characters, so that instead of year = "2011", it is year = "11"?

You can indeed use year(3:4); however, your string will still be four characters long, i.e. it will contain your two digits, and two blanks. To illustrate this, here's an example:

program trunc
   character(len=4) :: year = "2011"

   write(*,'(A,A,A)') '..', year, '..'
   year = year(3:4)
   write(*,'(A,A,A)') '..', year, '..'
end program trunc

This prints

..2011..
..11  ..

To really get "11" instead of "11 " you have to assign the value to a variable that can hold two characters only.

I think it's year(3:4) but don't quote me on it ;)

You can use year(3:4) with year declared as a deferred-length character to avoid trailing spaces. This is a Fortran 2003 feature so you need a compiler compatible with that, and you cannot initialize the variable in the declaration.

Example:

program deflen
   implicit none
   character(len=:), allocatable :: year 
   year = '2011'
   write(*,'(A,A,I0)') year,'_LEN=', LEN(year)
   year = year(3:4)
   write(*,'(A,A,I0)') year,'_LEN=', LEN(year)
end program deflen

This prints:

2011_LEN=4
11_LEN=2

Use the following:

character(4) :: year = "2011"
character(2) :: yr2

yr2 = trim(year(3:4))

Here yr2 is the intended two character string.