Python print Function

Last modified April 11, 2025

This comprehensive guide explores Python’s print function, which outputs text to the standard output stream. We’ll cover basic usage, formatting options, and practical examples of console output in Python.

Basic Definitions

The print function displays objects to the text stream, typically the console. It converts objects to strings, separates them with spaces, and ends with a newline by default.

Key characteristics: accepts multiple objects, handles string conversion, supports custom separators and line endings, and can redirect to files. It’s Python’s primary output mechanism.

Basic Usage

Here’s simple usage showing how print handles different types of objects and multiple arguments. This demonstrates its default behavior.

basic_print.py

Simple string

print(“Hello, World!”)

Multiple arguments

print(“The answer is”, 42)

Different types

print(“Pi is approximately”, 3.14159)

Mathematical expression

print(“2 + 2 =”, 2 + 2)

List output

print([1, 2, 3, 4, 5])

This example shows print’s versatility. It automatically converts numbers to strings, handles multiple arguments, and evaluates expressions.

By default, print separates arguments with spaces and ends with a newline. These behaviors can be customized as shown in later examples.

Custom Separators and Endings

The sep and end parameters control how print joins arguments and terminates output. This example demonstrates customization.

separators.py

Custom separator

print(“2025”, “04”, “11”, sep="-") # 2025-04-11

No separator

print(“Python”, “is”, “awesome”, sep="") # Pythonisawesome

Custom end character

print(“Loading”, end="… “) print(“Done!”) # Loading… Done!

Multi-line output

print(“First line”, end="\n\n”) print(“Third line”)

Tab-separated values

print(“Name”, “Age”, “City”, sep="\t") print(“Alice”, 30, “Paris”, sep="\t")

The sep parameter replaces the default space between arguments. The end parameter replaces the default newline at the end.

These features are useful for formatting output precisely, creating CSV/TSV data, or building progress indicators without line breaks.

File Output

The print function can write directly to files using the file parameter. This example shows file output and standard error redirection.

file_output.py

Writing to a file

with open(“output.txt”, “w”) as f: print(“This goes to a file”, file=f)

Appending to a file

with open(“log.txt”, “a”) as f: print(“New log entry”, file=f)

Writing to stderr

import sys print(“Error message”, file=sys.stderr)

Multiple file writes

with open(“data.csv”, “w”) as f: print(“Name,Age,Score”, file=f) print(“Alice,25,95”, file=f) print(“Bob,30,88”, file=f)

The file parameter accepts any file-like object with a write method. This includes standard streams like sys.stderr.

File output is buffered by default. For immediate writing, either flush the file or use flush=True parameter (Python 3.3+).

Formatted Output

The print function works with various string formatting techniques. This example shows f-strings, format(), and %-formatting.

formatting.py

f-strings (Python 3.6+)

name = “Alice” age = 30 print(f"{name} is {age} years old")

format() method

print("{} + {} = {}".format(5, 3, 5+3))

%-formatting

print(“Pi: %.2f” % 3.14159)

Column alignment

print("{:<10} {:>10}".format(“Item”, “Price”)) print("{:<10} {:>10.2f}".format(“Apple”, 0.99)) print("{:<10} {:>10.2f}".format(“Banana”, 1.25))

Multi-line formatted output

print(f"""
Name: {name} Age: {age} Score: {95} “”")

String formatting allows precise control over output appearance. f-strings (Python 3.6+) provide the most readable syntax for embedding expressions.

The example demonstrates number formatting, column alignment, and multi-line output. These techniques are essential for creating professional console output.

Advanced Features

This example explores less common print features like flush, printing iterables, and handling non-string types.

advanced.py

Flushing output immediately

print(“Loading…”, end="", flush=True) import time time.sleep(2) print(“Done!”)

Printing iterables with *

numbers = [1, 2, 3, 4, 5] print(*numbers, sep=", “) # 1, 2, 3, 4, 5

Printing dictionaries

person = {“name”: “Alice”, “age”: 30} print(“Person:”, person)

Custom object with str

class Point: def init(self, x, y): self.x = x self.y = y

def __str__(self):
    return f"Point({self.x}, {self.y})"

print(Point(3, 4)) # Point(3, 4)

Printing bytes

print(b"Hello”) # b’Hello'

The flush parameter forces immediate output, useful for progress indicators. The * operator unpacks iterables for printing.

Custom objects should implement str for meaningful print output. print handles bytes and other types by calling their string representation methods.

Best Practices

• Use f-strings: For clean, readable string formatting (Python 3.6+)

• Consider end parameter: For progress indicators without newlines

• Implement str: For custom objects to print meaningfully

• Use file parameter: For writing directly to files or stderr

• Format consistently: Maintain uniform output formatting

Source References

• Python print() Documentation

• Python Output Formatting

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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