Python Invoicer

   Python Invoicer

File handling is an important part of any application.

Python has several functions for creating, reading, updating, and deleting files.

File Handling

The key function for working with files in Python is the open() function.

The open() function takes two parameters; filename, and mode.

There are four different methods (modes) for opening a file:

"r" - Read - Default value. Opens a file for reading, error if the file does not exist

"a" - Append - Opens a file for appending, creates the file if it does not exist

"w" - Write - Opens a file for writing, creates the file if it does not exist

"x" - Create - Creates the specified file, returns an error if the file exists

f = open("demofile2.txt", "a")

f.write("Now the file has more content!")

f.close()

#open and read the file after the appending:

f = open("demofile2.txt", "r")

print(f.read())

In Python, you can assign a formatted print statement to a variable using f-strings (formatted string literals):

ame = "Alice"

age = 30

formatted_string = f"Hello, my name is {name} and I am {age} years old."

Calculate the invoice and print each line out to a file called lastname.txt

==============================

cust_first_name = input("Customer First name: ")

cust_last_name = input("Customer Last name: ")

file_ext = ".txt"

inv_name = cust_last_name + file_ext

f = open(inv_name, "a")

cust_address = input(" Address: ")

cust_city = input(" City: ")

cust_state = input(" State: ")

cust_zip = input(" Zip: ")

print(cust_last_name)

print(cust_address)

items = {"plates" : 3, "cups" : 1, "glasses" : 2}

for x in items:

    print(x, items[x])

no_plates = input("Number of Plates: ")

no_cups = input("Number of Cups: ")

no_glasses = input("Number of Glasses: ")

total_plates = int(no_plates) * int(items["plates"])

total_cups = int(no_cups) * int(items["cups"])

total_glasses = int(no_glasses) * int(items["glasses"])

total_charge = int(total_plates) + int(total_cups) + int(total_glasses)

inv_name = cust_first_name + " " + cust_last_name + "\n"

print(inv_name)

f.write(inv_name)

inv_address = cust_address + "\n"

print(cust_address)

f.write(inv_address)

print(cust_city)

inv_city = cust_city + "\n"

f.write(inv_city)

print(cust_state)

inv_state = cust_state + "\n"

f.write(inv_state)

print(cust_zip)

inv_zip = cust_zip + "\n"

f.write(inv_zip)

## line item for plates

price_plates = items["plates"]

inv_plates = f"You Bought {no_plates} number of plates at ${price_plates:.2f} = ${total_plates:.2f} dollars. \n"

f.write(inv_plates)

myplates = "You Bought {} number of plates at {} = {} dollars."

print(myplates.format(no_plates, items["plates"], total_plates))

## line item for cups

price_cups = items["cups"]

inv_cups = f"You Bought {no_cups} number of cups at ${price_cups:.2f} = ${total_cups:.2f} dollars. \n"

f.write(inv_cups)

mycups = " {} number of cups at {} = {} dollars."

print(mycups.format(no_cups, items["cups"], total_cups))

## line item for glasses

price_glasses = items["plates"]

inv_glasses = f"You Bought {no_glasses} number of glasses at ${price_glasses:.2f} = ${total_glasses:.2f} dollars. \n"

f.write(inv_glasses)

myglasses = " {} number of glasses at {} = {} dollars."

print(myglasses.format(no_glasses, items["glasses"], total_glasses))

print('==============================================================')

inv_total = f" Total Amount Due = ${total_charge:.2f} dollars. \n"

f.write("============================================================== \n")

f.write(inv_total)

mytotal = " Total Amount Due = {} dollars."

print(mytotal.format(total_charge))

f.close()

=========================================================

Results

python invoicer.py

Customer First name: John

Customer Last name: Iacovacci

 Address: 55 Daffodil Road

 City: Stamford

 State: CT

 Zip: 06903

Iacovacci

55 Daffodil Road

plates 3

cups 1

glasses 2

Number of Plates: 4

Number of Cups: 4

Number of Glasses: 4

John Iacovacci

55 Daffodil Road

Stamford

CT

06903

You Bought 4 number of plates at 3 = 12 dollars.

 4 number of cups at 1 = 4 dollars.

 4 number of glasses at 2 = 8 dollars.

=========================================================

 Total Amount Due = 24 dollars.

C:\WINDOWS\system32>cd /users

C:\Users>cd john

C:\Users\john>cd pyton

The system cannot find the path specified.

C:\Users\john>cd python

C:\Users\john\python>python invoicer.py

Customer First name: John

Customer Last name: Iacovacci

 Address: 55 Daffodil Road

 City: Stamford

 State: CT

 Zip: 06903

Iacovacci

55 Daffodil Road

plates 3

cups 1

glasses 2

Number of Plates: 4

Number of Cups: 4

Number of Glasses: 4

John Iacovacci

55 Daffodil Road

Stamford

CT

06903

You Bought 4 number of plates at 3 = 12 dollars.

 4 number of cups at 1 = 4 dollars.

 4 number of glasses at 2 = 8 dollars.

==============================================================

 Total Amount Due = 24 dollars.

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