Console Input & Output in Python

A beginner-friendly Python tutorial on how to print output in the terminal and take user input (text + numbers) using print(), sys.stdout, sys.argv, and input().

Console Output Basics

Console output means showing text in the terminal. Python provides a built-in function called `print()` to display messages and values. It is simple, powerful, and used everywhere — especially for debugging and CLI programs.

1. print() (Normal Output)

Use print() to display text. It automatically moves to the next line after printing.

2. Printing Variables (f-strings)

Use f-strings to insert variables inside strings easily.

3. Printing Without Automatic Newline

Use the `end` parameter of print() to control newline behavior.

Printing Using sys.stdout

For more control (like CLI tools), you can use `sys.stdout.write()` which does not automatically add a newline.

1. sys.stdout.write()

This prints exactly what you provide — without adding a newline.

Formatted Console Output

Python provides methods like `ljust()` and `rjust()` to align text. This helps create clean CLI tables.

1. ljust() and rjust() Basics

`ljust(width)` aligns text left. `rjust(width)` aligns text right.

2. Print a Simple Table

Create a clean aligned table in terminal.

Console Input (Reading User Data)

Python allows reading user input in two main ways: 1) sys.argv (command-line arguments) 2) input() (interactive input)

1. sys.argv (Command-Line Arguments)

Example: user runs `python app.py John 22`.

2. input() (Interactive Input)

Program asks a question and waits for user input.

3. Scan a Number (Single Number Input)

Convert string input to number and validate.

4. Scan Multiple Numbers (Space Separated)

User enters numbers like: 10 20 30