FUNCTIONS, an awesome topic I learnt today. It's a shortcut for all lazy i.e., smart people who don't wanna waste their time typing inputs for several times.

*What Is a Function?*

In programming, rather than repeatedly writing the same code , we write a function and use it whenever and whereever it is needed.

It helps to improve modularity, code organization and reusability.

So, now let's see how to create a function.

A function contains,

- function name - an identifier by which a function is called
- arguments - contains a list of values passed to the function
- function body - this is executed each time the function is called function body must be intended
- return value - ends function call and sends data back to the program

```
def function_name(arguments): # key function name(arguments)
statement # function body
statement
return value # return value
```

Some examples of how to use functions.

*#Write a function greet that takes a name as an argument and prints a greeting message.*

```
def greet(name):
return(f"Hello, {name}!")
greet("ABY")
Hello, ABY!
```

Here, we can replace __return__ by __print__ too.

*#Write a function sum_two that takes two numbers as arguments and returns their sum.*

```
def sum_two(a,b):
return a+b
result = add(3,7)
print(result)
10
```

*#Write a function is_even that takes a number as an argument and returns True if the number is even, and False if it is odd.*

```
def is_even(num):
return num % 2 == 0
num = 5
print(is_even(num))
False
```

*#Write a function find_max that takes two numbers as arguments and returns the larger one.*

```
def find_max(a,b):
if a > b:
return a
else:
return b
print(find_max(7,9))
9
```

*#Write a function multiplication_table that takes a number n and prints the multiplication table for n from 1 to 10.*

```
def multiplication_table(n):
for I in range (1,11)
result = n * i
print(f"{n} * {i} = {result}")
n = multiplication_table(int(input("Enter a no: ")))
```

and the result is,

```
Enter a no: 5 # I've entered 5
5 * 1 = 5
5 * 2 = 10
5 * 3 = 15
5 * 4 = 20
5 * 5 = 25
5 * 6 = 30
5 * 7 = 35
5 * 8 = 40
5 * 9 = 45
5 * 10 = 50
```

*#Write a function celsius_to_fahrenheit that takes a temperature in Celsius and returns the temperature in Fahrenheit.*

This is how we normally do it..

```
celsius1 = 27
fahrenheit1 = (celsius1 * 9/5) + 32
print(f"{celsius1}°C is {fahrenheit1}°F")
celsius2 = 37
fahrenheit2 = (celsius2 * 9/5) + 32
print(f"{celsius2}°C is {fahrenheit2}°F")
celsius3 = 47
fahrenheit3 = (celsius3 * 9/5) + 32
print(f"{celsius3}°C is {fahrenheit3}°F")
27°C is 80.6°F
37°C is 98.6°F
47°C is 116.6°F
```

It's cumbersome right??

Soo, what's the shortcut? Ofc using a function.

```
def celsius_to_fahrenheit(celsius):
return (celsius * 9/5) + 32
celsius = float(input("Celsius: "))
fahrenheit = celsius_to_fahrenheit(celsius)
print(f"{celsius}°C is {fahrenheit}°F")
Celsius: 37.5
37.5°C is 99.5°F
```

I've used input function to make it more compact...

*#Write a function power that takes two arguments, a number and an exponent, and returns the number raised to the given exponent. The exponent should have a default value of 2.*

```
def pow(num,exp = 2):
return num ** exp
result = pow(5,exp = 2)
print(f"The number {num} raised to power 2 is ",{result})
```

You can opt to use input fns and variables as well..

By now, it's understandable that for one problem we can use multiple

programs to solve it. It depends which we prefer to use.

.....

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