# recip.py
# Lillian Lee (LJL2) and Steve Marschner (SRM2)
# Apr 18, 2013

"""Demonstrate use of try/except statements"""


def recip1(x):
    """Return 1.0/x."""
    return 1.0/x


def recip2(x):
    """Return 1.0/x, or inf (infinity) if x is 0"""
    try:
        return 1.0/x
    except ZeroDivisionError:
        return float('Inf')


def recip3(x):
    """Return 1.0/x, or inf (infinity) if x is 0"""
    # try this one with input 'Lee' or 'Marschner'
    if x != 0:
        return 1.0/x
    else:
        return float('Inf')


def recip4():
    """Solicit a number from user, and return its reciprocal.
    If the user enters invalid input, re-prompt"""
    prompt = "Pick a non-zero number, and I'll print out the reciprocal: "
    while True:
        try:
            x = float(raw_input(prompt))
            return 1.0/x
        except ZeroDivisionError:
            print 'The number has to be NON-ZERO; please try again.'
        except ValueError:
            print 'The input has to be a NUMBER; please try again.'


def recip5():
    """Solicit a number from user, and return its reciprocal.
    If the user enters invalid input, re-prompt"""
    prompt = "Pick a non-zero number, and I'll print out the reciprocal: "

    goodinput = False  # has a valid input been given yet?
    while not goodinput:
        x = raw_input(prompt) #PROBLEM - x is a string.
                              # See is_float_literal below
        if not type(x) in [float, int]:
            print 'The input has to be a number; please try again.'
        elif x == 0:
            print 'The input has to be a number; please try again.'
        else:
            return 1.0/x


def is_float_literal(s):
    """True if string s contains a valid float literal."""

    has_digits = False
    i = 0
    if s[i] in "-+":
        i += 1
    while i < len(s) and s[i] in "0123456789":
        i += 1
        has_digits = True
    if i < len(s) and s[i] == '.':
        i += 1
        while i < len(s) and  s[i] in "0123456789":
            i += 1
            has_digits = True
    if i < len(s) and s[i] in "eE":
        i += 1
        if i < len(s) and s[i] in "-+":
            i += 1
        if i == len(s):
            return False
        while i < len(s) and  s[i] in "0123456789":
            i += 1
    return i == len(s) and has_digits

    assert is_float_literal("1")
    assert is_float_literal("10")
    assert is_float_literal("1.")
    assert is_float_literal(".1")
    assert is_float_literal("-.231")
    assert is_float_literal("1e10")
    assert is_float_literal("+1.0e10")
    assert is_float_literal("1.e10")
    assert is_float_literal(".1e10")
    assert is_float_literal(".1e+10")

    assert not is_float_literal("a")
    assert not is_float_literal(".")
    assert not is_float_literal("12e")
    assert not is_float_literal("12e+")
    assert not is_float_literal("e10")
    assert not is_float_literal(".e10")