# Exercise 32: Write a version of a palindrome recognizer that accepts a file name from the user, reads each line, and prints the line to the screen if it is a palindrome

palindrome.txt

A but tuba


radar
raddar
A car, a man, a maraca
A Santa at Nasa
Hello, World
Ah, Satan sees Natasha!
Aibohphobia
Air an aria.
Al lets Della call Ed Stella.
alula

py_exercise32.py

def is_palindrome(fname):
    f = open(fname)
    line = f.readline().lower()
    
    while line != "":
        i = 0        
        j = len(line.strip()) - 1 # -1 cuz index starts at 0
        while i <= j:
            # Read from LEFT
            while not line[i].isalpha() and i != j -1:  # j-1 so it doesn't add 1 to i before breaking loop
                i += 1
                
            # Read from RIGHT
            while not line[j].isalpha() and j != i:
                j -= 1
                
            #print(i, line[i], "|", j, line[j]) # check to visualize
            if line[i] == line[j]:
                i += 1
                j -= 1
                
            else:
                i, j = j, i
                
        if i >= j:  # see line 16, it adds to val before break >> go back before index was +/-
            i -= 1
            j += 1
            
        # BOOL Shortcuts
        line_not_empty = len(line.strip()) != 0
        is_alpha = line[i].isalpha() or line[j].isalpha()
        both_is_alpha = line[i].isalpha() and line[j].isalpha()
        
        if (not is_alpha or line[i] != line[j]) and line_not_empty:
            print("| False |", line.strip()) 
        
        if both_is_alpha and line[j] == line[i] and line_not_empty:
            print("| True  |", line.strip())
        
        # READ next line when i <= j
        line = f.readline().lower()

    f.close()

is_palindrome() using sting checkup

def is_palindrome(fname):

    f = open(fname)
    
    original = f.readline()
    while original != "":  # Read file until empty // cmdlinetips.com: ways to read files
        
        line = list(original.lower().strip())

        for char in line:
            
            if not char.isalpha():
            # OR if char not in "abcdefghijklmnopqrstuvwxyz":
                line.remove(char)
                
                if " " in line:
                    line.remove(" ")

        if list(reversed(line)) == line and len(line) != 0:  # len(line)... for blank \n lines
            print(original.strip()) # line comes w/ an "\n"                
                #print("(" + "".join(reversed(line)), "|", "".join(line) + ")\n") // CHECK                
            
        original = f.readline()
    
    f.close()

is_palindrome() - original w/ dictionaries and list

d = {}
for word in lines:
    word = list(word.lower())

    if len(word) == 0:
        lines.remove('\n')


    for char in word:
        if char not in "abcdefghijklmnopqrstuvwxyz":
            word.remove(char)
    print(word)

    d["".join(word)] = "".join(reversed(word))


i = 0
for key in d.keys():
    if d[key] == key:
        print(txt[i].rstrip())
        i += 1
    else:
        i += 1
print(d)