Fibonacci in Fortran

Welcome to the Fibonacci in Fortran page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

! In program name, - is not allowed
! works until 184 (Stop is not implemented)
program fibonacci

! Create the variables
character(26) :: low = 'abcdefghijklmnopqrstuvwxyz'                 ! Defines all lowercase letters. This is used to later scan for letters in the input as a test.
character(26) :: cap = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'                 ! Defines all uppercase letters. This is used to later scan for letters in the input as a test.
integer(kind = 16) :: previousnumber, currentnumber, addednumber, uppers, lowers, loop
character(len=10) :: argument                                      ! Defines the object we will be recieving. It will arrive as a charcters as the expectation is keyboard input.
                                                                   ! Fortran knows that 'argument' is user input, so we never need to set it to anything

! Define variables.
previousnumber = 0
currentnumber = 1
addednumber = 0

IF(COMMAND_ARGUMENT_COUNT().NE.1)THEN
    write(*,'(g0.8)')"Usage: please input the count of fibonacci numbers to output"
    STOP
ENDIF
  
CALL GET_COMMAND_ARGUMENT(1,argument)
    if (argument == "") then
    write(*,'(g0.8)')"Usage: please input the count of fibonacci numbers to output"
    STOP
endif

! Tests to make sure we have recieved NUMBERS and not anything else. These act as flags that will later end the program.
uppers = scan(argument, cap)    ! This will look for uppercase letters in the recieved string. If any letter is uppercase, uppers will be updated.
lowers = scan(argument, low)    ! This will look for lowercase letters in the recieved string. If any letter is lowercase, lowers will be updated.

! Will see if there are any uppercase, if so, print an error.
if (uppers > 0) then            
  write(*,'(g0.8)')"Usage: please input the count of fibonacci numbers to output"
  STOP
endif

! Will see if there are any lowercase, if so, print an error.
if (lowers > 0) then            
  write(*,'(g0.8)')"Usage: please input the count of fibonacci numbers to output"
  STOP
endif


! If all checks pass, we will enter this section.  If non pass, we will not reach this point
! Enter a loop
read (argument, '(I10)') loop
do i = 1, loop
    write(*,'(5g0)') i, ": ", currentnumber         ! Print current iteration, and current number
    addednumber = previousnumber + currentnumber    ! Replace the value of 'added number' with both 'current number' and 'previous number'
    previousnumber = currentnumber                  ! Replace the value of 'previous number' with 'current number'
    currentnumber = addednumber                     ! Replace the value of 'current number' with 'added number'
end do

end program fibonacci

Fibonacci in Fortran was written by:

• Butenkite

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.