1. file_handle.py
2. robust_error_handling.py
3. yearborn2.py
4. yearborn.py
5. years_dictionary2.py
6. years_dictionary.py

# Demonstrate file handling exception
# Examples of errors:
#   - file not found
#   - don't have permission on the file
# Sara Sprenkle

import sys

def main():
    infileName = input("What file do you want to read? ")
    
    # put the "correct"/"usual" behavior within the try
    try:
        inFile = open(infileName, "r")
        # normally, we would do some sort of processing of the file here.
        inFile.close()
    except IOError as exc: # exc is the name of the raised exception
        print("Error reading \"" + infileName + "\".")
        # could be a variety of different problems, so print out
        # the exception
        print(exc)
        print(type(exc)) # not helpful output for the user; just for demo purposes
        sys.exit(1)

    outfileName = input("What file do you want to write? ")
   
    try:
        outFile = open(outfileName, "w")
        # normally, we would do some sort of processing of the file here.
        outFile.close()
    except IOError as exc:
        print("Error writing \"" + outfileName + "\".")
        print(exc)
        print(type(exc)) # not helpful output for the user; just for demo purposes
        # no need to exit here because there is nothing else to do.
    
main()

# Demonstrate file handling exception
# Examples of errors:
#   - file not found
#   - don't have permission on the file
# Sara Sprenkle

import sys

def main():
    
    print("Let's do some more robust error handling")
    
    isFileRead = False
    
    while not isFileRead:
        
        infileName = input("What file do you want to read? ")
    
        # put the "correct"/"usual" behavior within the try
        try:
            inFile = open(infileName, "r")
            # normally, we would do some sort of processing of the file here.
            inFile.close()
            isFileRead = True
        except IOError as exc: # exc is the name of the raised exception
            print("Error reading \"" + infileName + "\".")
            # could be a variety of different problems, so print out
            # the exception
            print(exc)

        print()
        
    print("File read!  now, let's do something with it...")
    
main()

# Demonstrate validating user input
# by CSCI111

import sys

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

    try:
        age = int(input("Enter your age: "))
        currentyear = int(input("Enter the current year: "))
    except ValueError:
        print("Error: Your input was not in the correct form.")
        print("Enter integers for your age and the current year")
        sys.exit(1)
    
    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:
        birthyear=currentyear - age
        print("You were either born in", birthyear, "or", birthyear-1)


main()

# Demonstrate validating user input
# by CSCI111

import sys

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

    try:
        age = int(input("Enter your age: "))
        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(1)
    
    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:
        birthyear=currentyear - age
        print("You were either born in", birthyear, "or", birthyear-1)


main()

# Given a file of the form <firstname> <classyear>,
# report how many students are in each class year
# by CSCI 111

FILENAME="data/roster.dat"

# open the file for reading
yearsFile = open(FILENAME, "r")

# create our accumulator dictionary
gradYearToCount = {}

# go through each line
for line in yearsFile:
    # split at the space into the name and the year
    rosterList = line.split()
    year = rosterList[1]
    
    # is this grad year in the dictionary?
    if year in gradYearToCount:
    # if it is, accumulate, update the count for that grad year
        gradYearToCount[year] += 1
        
        # Alternative solution
        #count = gradYearToCount[year]
        #count += 1
        #gradYearToCount[year] = count
        
    # else, create a new key with a value of 1
    else:
        gradYearToCount[year] = 1
    
yearsFile.close()

#print(gradYearToCount)

# Better yet, display in a nice way:

for gradyear in sorted(gradYearToCount):
    numStudents = gradYearToCount[gradyear]
    print( numStudents, "student(s) are in the class of", gradyear)

# Given a file of the form <firstname> <class>
# creates a mapping between the first names and class
# by CSCI 111

FILENAME="data/roster.dat"

# open the file for reading
yearsFile = open(FILENAME, "r")

# create our accumulator dictionary
nameToYear = {}

# go through each line
for line in yearsFile:
    # split at the space into the name and the year
    rosterList = line.split()
    
    # key is the name, value is the year
    name = rosterList[0]
    year = rosterList[1]
    
    # add mapping into the dictionary
    nameToYear[name] = year
    
yearsFile.close()

print(nameToYear)

#repeatedly (until the user enters nothing)
while True:
    # prompt for the student name and display their class year
    studentName = input("What is the student's name? ")
    
    if studentName == "":
        break
    
    if studentName in nameToYear:
        year = nameToYear[studentName]
        print(studentName, "is expected to graduate in", year)
    else:
        print(studentName, "is not on the roster")