if condition problem

Since I didn't find any part of the standard stating out sequence of judging parallel conditions, I would like to ask if anyone has even met the situation like:

function Test(str)
    implicit none

    character(*), intent(in) :: str

    if(LEN(str) >=2 .AND. str(2:2) == 's')then
        ! do something...
    end if

end function Test

In the if statement above, there are two conditions. If the dummy argument str we passed in was just a single character assume 'a', there is going to be an error with ivf compiler as condition str(2:2)=='s' is referring to index number 2 of 'a' which simply doesn't exist. So in Fortran, is it true that conditions within a judging statement are all be judged every time of execution ?  In other words no left-to-right judging sequence ? About this case I See difference in C# while since condition LEN(str)>=2 is false, the if block will be skipped and, no matter true or false the second condition is, it is not ever judged so it's legal to write these conditions together, but not in Fortran. Appreciate any explanation.