WEBVTT

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In this video, we will learn how to use functions in Python, how to build an interactive

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program.

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We are creating a program that functions as a mini toolbox with two tools, a calculator

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for basic arithmetic operations, and a temperature converter between Celsius and Fahrenheit.

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We get to choose which tool to use, and the program will guide you step-by-step.

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In Python, functions help us organize code by breaking tasks into smaller, reusable

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parts.

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Defining functions for operations Here, we use functions to perform basic

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arithmetic operations like addition, subtraction, multiplication, and division.

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Def add, a b, return, a plus b, def subtract a b, return a minus b, def multiply a b, return

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a asterisk b, def divide a b, return error.

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If b is equal to 0, else a by b, each function takes two numbers as input and returns the result.

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Def invalid operation a, b, return invalid.

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Invalid operation a, b is used to return invalid, if the user enters an incorrect operation.

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Function-based calculator, def calculator, print, choose, add, subtract, multiply, divide.

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Operation is equal to input, enter operation dot lower.

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Sum 1, num 2 is equal to float, input, first number, float, input, second number.

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The calculator function asks the user for an operation and the input of two numbers.

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Operations is equal to add add, subtract, subtract, multiply, multiply, divide, divide.

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Expanded function is equal to operations dot get, operation, invalid operation, print, result.

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Selected function num 1 num 2, it uses addictionary operations to call the correct function based

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on the user's choice.

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Temperature converter function.

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Temperature converter function contains two nested functions, c to f, c, convert Celsius

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to Fahrenheit, f to c, f, converts Fahrenheit to Celsius, def temperature converter, def

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c to f, c, return, c, asterisk 9 by 5, plus 32, def to c, f, return, f, minus 32, asterisk

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5 by 9, print, convert temperature, c to f or f to c, choice is equal to input, type

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c or f, dot upper, temp is equal to float, input, enter temperature, print, result, c to

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f, temp, if choice is equal to c, else f to c, temp, degree, it prompts the user to choose

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a conversion type, asks for input, and then calls the appropriate function to perform

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the conversion, main function to control program flow, def main, print, choose a program,

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1, calculator, 2, temperature converter, choice is equal to input, enter 1 or 2, if choice

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is equal to 1, calculator, else if, choice is equal to 2, temperature converter, else,

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print, invalid choice, try again, return main, main function starts by asking the user

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to choose between the calculator and temperature converter, if user enters an invalid choice,

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it prompts them to try again, after running 1 function, the user gets an extended menu

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with 3 options, use the calculator again, use the temperature converter again, or exit

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the program, here we are using a wild loop to keep showing this menu until the user chooses

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to exit, allowing them to perform multiple calculations or conversions without restarting

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the program, while true, print, choose 1, calculator, 2, temperature converter, 3, exit,

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choice is equal to input, enter 1, 2, or 3, if choice is equal to 1, calculator, else

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if, choice is equal to 2, temperature converter, else if, choice is equal to 3, print, exiting

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program, break, else, print, invalid choice, try again, main, save the program with a name

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like function-based calculator.py, click the run button and test the program by choosing

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different options, first we choose calculator and select add, we enter numbers 20 and 30,

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and the program displays, result 50, next we choose calculator again and select multiply,

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we enter 6 and 5, and the program displays, result, 30, now we select temperature converter,

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choose seat, and enter 20 degrees Celsius, the program displays, result, 68.0 degrees

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Fahrenheit, finally we choose exit and the program stops, functions make programs efficient

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and organized, this program used multiple functions for clarity and ease of use.