ImportantFunctions.md

Important Functions

Python provides many built-in functions that are very useful. We have already seen a few of them, such as print() and type(). Below is a list of some important functions that will be helpful as you continue learning:

• print() - displays text in the terminal
• type() - returns the type of a value
• input() - receives input from the user
• len() - returns the length of a string
• round() - rounds a float

The functions discussed earlier will be skipped here. If needed, please refer back to the previous topics.

input()

This function pauses the program and waits for the user to type something. Whatever the user enters is then returned by the function and can be stored in a variable for later use:

text = input()

print(text)

This function can also take a string as a parameter. The string will be displayed to the user before they are asked for input:

name = input("Enter your name: ")

print(name)

You can also use this function directly inside print() if the value is not going to be reused:

print(input("Enter your name: "))

If you want to get integers (or other types of numbers) from the user, be careful: input() always returns a string. You will need to convert it to the correct type before using it in calculations.

number = input("Enter your number: ")

print(type(number)) # Output: <class 'str'>

In this example you can just cast it to an int so you can use it in calculations and such.

number_1 = int(input("Enter the first number: "))
number_2 = int(input("Enter the second number: "))

print(number_1 + number_2)

len()

This function returns the number of elements in a value. For example, it can count the number of characters in a string, or the number of items in a list (we’ll learn about lists later).

number_of_char = len("Hello world!")

print(number_of_char) # Output: 12

round()

This function rounds a float to the nearest integer. Be careful: Python uses a method called banker’s rounding. This means that if a number is exactly halfway between two integers, it rounds to the nearest even number.

print(round(2.3)) # Output: 2
print(round(2.5)) # Output: 2
print(round(2.7)) # Output: 3
print(round(3.5)) # Output: 4
print(round(3.3333)) # Output: 3
print(round(3.75)) # Output: 4

You can also pass a second argument to specify the number of decimal places to round to:

print(round(1.333333, 2)) # Output: 1.33
print(round(5.72, 1)) # Output: 5.7

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