Though Fortran is a programming language that is very easy to learn and execute, there can be some problems associated with it. A student might come across some issues.
Over the years we have discovered several glitches with the Fortran 90. Let’s discuss these issues:

1. A problem with an optional argument: Following is an example of how an optical argument can prove dangerous.
   
   

   
   subroutine print_char(this,header)
            character(len=*), intent (in) :: this
            logical, optional, intent (in) :: header
     ! THIS IS THE WRONG WAY
            if (present(header) .and. header) then
                print *, 'This is the header '
            endif
            print *, this
            end subroutine print_char
            subroutine print_char(this,header)
            character(len=*), intent (in) :: this
            logical, optional, intent (in) :: header
     ! THIS IS THE RIGHT WAY
            if (present(header)) then
               if (header) print *, 'This is the header '
            endif
            print *, this
            end subroutine print_char
   

   This can at times be dangerous as the compiler evaluates the header function before the current operation. In the absence of a header argument, an out of bound memory reference could take place, this could result in the failure of your operation.
2. Problem with intent (out): To avoid the problem of intent(out), intent(in-out) should be used.
3. Non-advancing I/O: It is the general assumption that string I/O in other programming languages are the same as the Non-advancing I/O in Fortran 90. But, let me tell you, this assumption is false.
4. Glitch with the locally initialized variable: Students can sometimes be ignorant or due to lack of knowledge, they can make mistakes while dealing with locally initiated variables. You should be careful while initiating a locally drawn variable.
5. Calling Fortran style routine could prove problematic: Fortran assignment help, students in need of it must approach an adept professional who is capable of identifying these problems, which are very subtle. With a little help and a little hard work, problem like this in your homework could prove non-existent.
6. Problem with an interface to Fortran 77: The interface to Fortran style subroutine must be executed with the Fortran programming language style construct.
7. Function overloading: In the Fortran language; to be more specific the Fortran 90; you have the option of reusing the same function name for different operations. It can work as long as the codes defined have different arguments.
8. Undefined pointers: A student while working on his assignment must be extra careful with pointers. Pointers are very much prone to creating an error. Pointers should be used only in the case that no allocatable variable is possible. If such a case occurs, pointers become a necessity and should be used.