def count_words(filename):
    """计算一个文件中有多少字"""
    try:
        with open(filename) as f_obj:
            contents = f_obj.read()
    except FileNotFoundError:
        msg = "sorry, the file" + filename + " does not exist"
        print(msg)
    else:
        words = contents.split()
        number_words = len(words)
        print("the file" + filename + "has about " + str(number_words) + " words")

filename = 'alice.txt'
count_words(filename)