Question

Python Programming: Why do I get UnboundLocalError? What does this mean and how can I fix it?

Question: Write a function check_move(column, row) which returns a string describing a chess move to a given row and column on the chess board. Your program must check if the row and column entered are both valid. The column in a chess board is a letter ranging from A to H or a to h (inclusive) and the row is a number between 1 and 8 (inclusive).

• column will be given to your function as a string and row will be given as an integer
• If both coordinates are valid, such as 'E' and 2, your function must return 'The piece is moved to E2.'

• Write a new version of check_move where, when there is an error in the chess move, the returned message specifies whether it is column or row value that is out of range:

• If the column value is out of range, return 'The column value is not in the range a-h or A-H!'.
• If the column value is in range but the the row value is out of range, return 'The row value is not in the range 1 to 8!'.

• Your function should behave like this:

  >>> check_move('B', 4)

  'The piece is moved to B4.'

  >>> check_move('b', 4)

  'The piece is moved to B4.'

• Your function should now work like this for invalid arguments:

  >>> check_move('I', 4)

  'The column value is not in the range a-h or A-H!'

  >>> check_move('F', 9)

  'The row value is not in the range 1 to 8!'

  >>> check_move('I', 9)

  'The column value is not in the range a-h or A-H!'

Here is my code, and how can I fix it?

def check_move(column,row):

if len(column) == 1 and (column in 'ABCEDFGH' or column in 'abcedfgh') and \
row in range(1, 9):
column = column.upper()
message = 'The piece is moved to ' + column + str(row) + '.'
else:
if (column not in 'ABCEDFGH' or column not in 'abcdefgh') and \
row in range(1, 9):
message = 'The column value is not in the range a-h or A-H!'
elif (column in 'ABCEDFGH' or column in 'abcedfgh') and \
row not in range(1, 9):
message = 'The row value is not in the range 1 to 8!'
return message

Answer 1

#forget to mention one condition in the program is column and row both are not in the range we need to righh

first condition column in range row not in range

second condition column not in range row in range

third condition both are column and row not in range

then only didn't get unbounderror

#source code:

def check_move(column,row):
   if len(column) == 1 and (column in 'ABCEDFGH' or column in 'abcedfgh') and row in range(1, 9):
       column = column.upper()
       message = 'The piece is moved to ' + column + str(row) + '.'
   else:
       if (column not in 'ABCEDFGH' or column not in 'abcdefgh') and row in range(1, 9):
           message = 'The column value is not in the range a-h or A-H!'
       elif (column in 'ABCEDFGH' or column in 'abcedfgh') and row not in range(1, 9):
           message = 'The row value is not in the range 1 to 8!'
       elif (column not in 'ABCEDFGH' or column not in 'abcedfgh') and row not in range(1, 9):
           message = 'The column value is not in the range a-h or A-H! and The row value is not in the range 1 to 8!'
   return message
print(check_move('I', 9))

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