4-7

#! /usr/bin/env python3.2
# -*- coding: utf-8 -*-

# main.py
""" Task: Exercise 4.7:
    Rewrite the grade program from the previous chapter using a function called
    computegrade that takes a score as its parameter and returns a grade as a
    string.
    Score Grade
    > 0.9 A
    > 0.8 B
    > 0.7 C
    > 0.6 D
    <= 0.6 F
    Program Execution:
    Enter score: 0.95
    A
    Enter score: perfect
    Bad score
    Enter score: 10.0
    Bad score
    Enter score: 0.75
    C
    Enter score: 0.5
    F
    Run the program repeatedly to test the various different values for input.
"""

# Functions
def determine_grade(score):
    """
    Determines the grade of a given score (string or float/int)
    Returns grade
    """
    grade = None
    try:
        score = float(score)
        if score < 0.0 or score > 1.0:
            raise 1         # simulates an error
        elif score > 0.9:
            grade = "A"
        elif score > 0.8:
            grade = "B"
        elif score > 0.7:
            grade = "C"
        elif score > 0.6:
            grade = "D"
        elif score >= 0:
            grade = "F"
        else:
            raise 1         # simulates an error
    except:
        grade = "Bad score"

    return grade

# Main
loop = True
while loop:
    score = None
    grade = None
    # Enter score
    while score == None:
        try:
            score = float(input("Enter score: "))
        except ValueError:
            score = None
            print("Invalid value!")
            continue
        except:
            score = None
            print("Error")
            continue
        if score < 0 or score > 1:
            score = None
            print("Please enter a value between 0.0 and 1.0!")
            continue
    grade = determine_grade(score)
    print("The grade of " + str(score) + " is " + str(grade) + ".\n")
    print("Do you want to enter a new score?")
    try:
        choice = input("(Y/N): ")
    except:
        choice = 'N'
    if choice.upper() == 'Y' or choice.upper() == 'YES':
        # 'y', 'Y', 'yes', 'yEs', ... 'YES' are valid
        continue
    else:                       # everything else is invalid
        loop = False            # and stops the program

# test
print("\nTesting string parameter in determine_grade(score):")
print("Score: 0.815\t\tResult: " + str(determine_grade("0.815")))
print("Score: 1.337\t\tResult: " + str(determine_grade("1.337")))
print("Score: lagerregal\tResult: " + str(determine_grade("lagerregal")))
print("Score: -0.02\t\tResult: " + str(determine_grade("-0.02")))
print("Score: 0.699999999\tResult: " + str(determine_grade("0.699999999")))
print("Score: 0.700000001\tResult: " + str(determine_grade("0.700000001")))