Python Programming for Lazy Beginners: A Simple and Easy Tutorial

CHAPTER 8

But if you don't use flush, Python will wait until the sleep function is done before printing the update, which means the user won't see anything until the script is finished. That's no good!

But if you use the flush parameter, you can force Python to reveal its output immediately, even if it's still buffering. This means the user will see each update as soon as it's printed, and they won't have to wait until the end of the script to see what's going on.

Here's an example of how you can use flush to print progress updates:

import time

for i in range(10):
    print(f"Progress: {i+1}/10",, flush=True)
    time.sleep(1)

In this example, we're using the end parameter to print the progress update on the same line (using the \r character to move the cursor to the beginning of the line), and we're using flush=True to force Python to write the output immediately, even though it's still buffering. This means that the user will see the progress update in real-time, even though the script is pausing for a second between each update.

So if you ever feel like Python is holding back on you, just use the flush parameter to reveal its hidden output

different methods to format output in Python

One common way to format output in Python is to use string concatenation with the + operator. For example, you might have a program that prompts the user for their name and age, and then prints out a greeting with their information:

name = input("What is your name? ")
age = input("What is your age? ")
print("Hello, " + name + "! You are " + age + " years old.")

While this method is simple and easy to understand, it can become unwieldy and difficult to read if you have a lot of variables to concatenate. That's where string interpolation comes in!

String interpolation allows you to embed variables directly in a string using special syntax. In Python, there are several ways to do this. One common way is to use the % operator, like this:

name = input("What is your name? ")
age = input("What is your age? ")
print("Hello, %s! You are %s years old." % (name, age))

In this example, %s is a placeholder that will be replaced with the value of name or age when the string is printed. The values themselves are passed as a tuple to the % operator.

Another way to do string interpolation in Python is to use f-strings, which were introduced in Python 3.6. F-strings allow you to embed variables directly in a string using curly braces {}. For example

name = input("What is your name? ")
age = input("What is your age? ")
print(f"Hello, {name}! You are {age} years old.")

In this example, the variables name and age are enclosed in curly braces, and Python will automatically substitute their values when the string is printed.

Yet another way to format output in Python is to use the format() method. This method allows you to specify placeholders in a string using curly braces {} and then fill in those placeholders with variables or values using the format() method. For example:

name = input("What is your name? ")
age = input("What is your age? ")
print("Hello, {}! You are {} years old.".format(name, age))