Convert repeating decimals to fractions.

Repeating decimals to fraction.py

import sys

def err(section):
    print("ERROR [{section}]: Bad input (not a number)".format(section=section))
    sys.exit(1)

def stoi(s):
    return int("".join(("0" + s)))

def int_repeat(n, k):
    x = 1
    for _ in range(k - 1):
        x = x * 10 + 1
    return n * x

def gcd(x, y):
    a = max(x, y)
    b = min(x, y)
    while b > 0:
        temp = a % b
        a = b
        b = temp
    return a

while True:
    inp = input().lower()
    if inp[0:4] == "exit":
        sys.exit(0)

    inp.replace(",", ".")

    # Substract 1, 2 because chars '(' and '.' will be removed from string
    dot = inp.find(".") - 1 # dot index
    a = inp.find("(") - 2 # repetitive decimals init index -> '('

    inp = inp.replace("(", "").replace(")", "").replace(".", "")

    num = 0
    den = 0

    if inp.isdigit():
        if dot >= 0:
            if a >= 0:
                ntimes = 1
                diff = abs(a - dot)
                if diff > 1: # Convert non repetitive decimal to integer side
                    a = dot + diff
                    ntimes = pow(10, diff)

                intpart_s = inp[:a+1] # integer part (str)
                decpart_s = inp[a+1:] # repetitive decimal part (str)

                intpart = stoi(intpart_s) # integer part (int)
                decpart = stoi(decpart_s) # repetitive decimal part (int)

                exp = pow(10, len(decpart_s)) # 10^(non repetitive decimal places)

                num = intpart * exp + decpart - intpart
                den = int_repeat(9, len(decpart_s)) * ntimes
            else:
                intpart_s = inp[:dot+1] # integer part (str)
                decpart_s = inp[dot+1:] # decimal part (str)

                intpart = stoi(intpart_s) # integer part (int)
                decpart = stoi(decpart_s) # decimal part (int)

                exp = pow(10, len(intpart_s)) # 10^(integer places)

                num = intpart * exp + decpart
                den = exp
        elif dot < 0:
            num = int(inp)
            den = 1
    else:
        err(1)

    gcd_num_den = gcd(num, den)

    if gcd_num_den == 1:
        print("{num}/{den} = {res}\n".format(num=num, den=den, res=num/den))
    else:
        num_s = num // gcd_num_den # numerator simplified
        den_s = den // gcd_num_den # denominator simplified
        print("{num_s}/{den_s} = {num}/{den} = {res}\n".format(num=num, den=den, res=num/den, 
                                                                num_s=num_s, den_s=den_s))

Usage: use (, ) to denote the repeating part.
Samples:
10.22(3) = 10.223333333333...
35.29(45) = 35.294545454545...