1. file_handle.py
2. mystery.py
3. twod_exercises.py
4. yearborn.py

# Demonstrate file handling exception
# Sara Sprenkle

import sys

def main():
    infileName = input("What file do you want to read? ")
    
    try:
        inFile = open(infileName, "r")
        # normally, would be doing some sort of processing of the file here.
        inFile.close()
    except IOError as exc: # exc is the name of the thrown exception
        print("Error reading \"" + infileName + "\".")
        # could be a variety of different problems, so print out
        # the exception
        print(exc)
        sys.exit(1)

    outfileName = input("What file do you want to write? ")
   
    try:
        outFile = open(outfileName, "w")
         
        outFile.close()
    except IOError as exc:
        print("Error writing \"" + outfileName + "\".")
        print(exc)
    
main()

# Practice with 2D lists
# by Sara Sprenkle

def main():
    matrix = createMatrix()
    print("Before:")
    print(matrix)
    mystery(matrix)
    print("After:")
    print(matrix)

def mystery(a):
    """ "run" this on A, at right """
    for row in range( len(a) ):
        for col in range( len(a[0]) ):
            if row == col:
                a[row][col] = 42
            else:
                a[row][col] += 1

def createMatrix():
    a0 = list(range(1,5))
    a1 = list(range(5,9))
    a2 = list(range(9,13))
    a = []
    a.append(a0)
    a.append(a1)
    a.append(a2)
    return a

main()

# Practice with 2D Lists
# Sara Sprenkle

def main():
    rows = int(input("How many rows? "))
    columns = int(input("How many columns? "))

    print()
    print("Correct Matrix Creation:")
    print('-'*30)
    matrix = create2DList(rows, columns)
    print(matrix)

    print("\nAssigning matrix[1][2]=3")
    matrix[1][2] = 3
    print("Result: ")
    print(matrix)

    print()
    print("*"*55)
    print("Incorrect Matrix Creation:")
    print('-'*30)

    matrix = noCreate2DList(rows, columns)
    print(matrix)

    print("\nAssigning matrix[1][2]=3")
    print("Result: ")
    matrix[1][2] = 3
    print(matrix)


def create2DList(rows, cols):
    """Returns a two-dimensional list filled with 0s that is 'rows' tall and
    'cols' wide."""
    twodlist = []
    for row in range(rows):
        row = []
        for col in range(cols):
            row.append(0)
        twodlist.append(row)
    return twodlist

def noCreate2DList(rows, cols):
    """Does not create a 2D list because each 'row' points to the same point in
    memory."""
    
    twodlist = []
    onerow = []
    for col in range(cols):
        onerow.append(0)
    for row in range(rows):
        twodlist.append(onerow)
        
    return twodlist
    

main()

# Demonstrate validating user input
# Modified from a student's code from lab assignment

import sys

def main():
    #Program mission statement
    print("This program determines your birth year")
    print("given your age and the current year \n")

    try:
        age = int(input("Enter your age: "))
        # note difference if use eval instead of int in above 
        currentyear = int(input("Enter the current year: "))
    except:
        print("ERROR: Your input was not in the correct form.")
        print("Enter integers for your age and the current year")
        sys.exit()
    
    if age < 0 or age > 115:
        print("Come on: you have to be a reasonable age.")
    elif currentyear < 0:
        print("You need to have a positive year.")
    else:
        #Subtract age from current year
        birthyear=currentyear - age
        #Display output to the user
        print("You were either born in", birthyear, "or", birthyear-1)


main()