Fortran Palindrome

Question

I am to write a fortran program to determine if a user character input is a palindrome using loops. What I don't understand is how to write code to see if the first and last characters are the same. Can someone please explain this to me and point me in the right direction?

Answer 1

'OLD FORTRAN 77

program hello

Print *, "Hello World!"

Implicit None

CHARACTER(Length=1) :: LeftChar

CHARACTER(Length=1) :: RightChar

CHARACTER(Length=25) :: InputStr

'Compares the characters at iLeft and iRight: if they DIFFER then it's not a palindrome!!!!

iLeft :: Integer

iRight :: Integer

iPalindromeFlag :: Integer

InputStr = "ABBA"

iLeft = 1

iRight = Len(inputStr)

iPalindromeFlag = 1

do while (iLeft <= iRight)

LeftChar = InputStr(iLeft:1)

RightChar = InputStr(iRight:1)

if (UPPER(LeftChar)/=Upper(RightChar)) then 'they are not the same, so not a palindrome

iPalindromeFlag = 0 'sets the flag to false and bails out

exit

end if

'moves the pointers

iLeft = iLeft + 1

iRight = iRight - 1

end do

print *,iPalindromeFlag

end program Hello