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Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
Build a Secure Password Strength Checker in Python
A Python function that evaluates password strength based on length and character diversity, returning Weak, Moderate, or Strong.
import re
def password_strength(password: str) -> str:
score = 0
if len(password) >= 8:
score += 1
if re.search(r'[a-z]', password):
score += 1
if re.search(r'[A-Z]', password):
score += 1
if re.search(r'\d', password):
score += 1
if re.search(r'[!@#$%^&*(),.?":…Find Data From a String in Python: Stats, Clean, Keywords
Three helper functions for beginners: compute character/word/sentence stats, normalize whitespace and case, and extract unique sorted keywords from a string.
def get_text_stats(text):
"""Return basic statistics about a string."""
words = text.split()
sentences = text.replace('!', '.').replace('?', '.').split('.')
sentences = [s for s in sentences if s.strip()]
return {
'characters': len(text),
'words': len(words),
'sentences': le…Find Most Frequent Character in a String in Python
Count character frequencies in a Python string using a dictionary and return the character that appears most often with a max() key function.
def most_frequent_char(s: str) -> str:
if not s:
return ""
char_count = {}
for ch in s:
char_count[ch] = char_count.get(ch, 0) + 1
max_char = max(char_count, key=char_count.get)
return max_char
if __name__ == "__main__":
text = "programming"
result = most_frequent…Find the Longest Word in a Sentence in Python
Splits a sentence into words and returns the longest one using the built-in max() function with len as the key.
def find_longest_word(sentence: str) -> str:
words = sentence.split()
if not words:
return ""
return max(words, key=len)
if __name__ == "__main__":
test_sentence = "The quick brown fox jumps over the lazy dog"
longest = find_longest_word(test_sentence)
print(f"Longest word: '{longest}'…How to Build a Text Processor in Python
This code defines functions to count words, sentences, and find the longest word in a text, then prints basic statistics like uppercase and lowercase versions.
def count_words(text):
return len(text.split())
def count_sentences(text):
sentence_endings = ".!?"
count = 0
for char in text:
if char in sentence_endings:
count += 1
return count
def longest_word(text):
words = text.split()
if not words:
return ""
retur…How to Check if a String Starts With a Prefix Case-Insensitively in Python
This code defines a function that checks if a string starts with a given prefix, ignoring case, using the lower() method.
def starts_with_case_insensitive(text, prefix):
"""Check if a string starts with a given prefix, ignoring case."""
return text.lower().startswith(prefix.lower())
if __name__ == "__main__":
test_strings = [
("Hello World", "hello"),
("Python Programming", "PYTHON"),
("Data Science"…How to Check if a String is Numeric in Python
This code provides a function to determine if a string represents a valid numeric value using Python's built-in float() conversion.
def is_numeric(s):
"""Check if a string represents a valid numeric value."""
try:
float(s)
return True
except (ValueError, TypeError):
return False
if __name__ == "__main__":
test_cases = ["123", "-45.67", "3.14e10", "0x1A", "abc", "12.5.6", " 42 ", ""]
for case in test_c…How to Compare Two Strings in Python
Compares two string values and returns a detailed report with equality, case-insensitive comparison, lengths, and uppercase versions.
def compare_data(first_value, second_value):
"""Compare two string values and return a report."""
if first_value == second_value:
status = "MATCH"
else:
status = "DIFFER"
return {
"first_value": first_value,
"second_value": second_value,
"status": status,
…How to Convert Data to Strings in Python
Convert common data types like bytes, numbers, containers, and None to readable strings with a safe helper function.
def to_str(value):
"""Convert common types to a readable string, safe for beginners."""
if isinstance(value, bytes):
return value.decode("utf-8")
if isinstance(value, (dict, list, tuple, set)):
return str(value)
if value is None:
return ""
return str(value)
if __name__ == …How to Convert camelCase to snake_case in Python
Convert camelCase strings to snake_case using a simple Python function that inserts underscores before uppercase letters and lowercases everything.
def camel_to_snake(s):
result = ""
for i, char in enumerate(s):
if char.isupper() and i > 0:
result += "_"
result += char.lower()
return result
if __name__ == "__main__":
test_cases = ["camelCase", "helloWorld", "thisIsACoolExample", "already_snake", "UPPER"]
for case i…How to Detect if a String Contains Only ASCII in Python
This code defines a function that checks whether every character in a given string is an ASCII character (Unicode code point < 128) and demonstrates it with multiple test cases.
def is_ascii_only(text: str) -> bool:
"""Return True if all characters in text are ASCII, False otherwise."""
return all(ord(char) < 128 for char in text)
if __name__ == "__main__":
# Test cases
samples = [
"Hello, world!",
"Café au lait",
"日本語テキスト",
"ASCII only 123",
…How to Encode and Decode UTF-8 in Python
Convert a Python string to UTF-8 bytes with .encode() and back to text with .decode(), with a simple demo function.
def encode_decode_demo(text: str):
encoded = text.encode("utf-8")
decoded = encoded.decode("utf-8")
print(f"Original string: {text}")
print(f"Encoded bytes: {encoded}")
print(f"Decoded string: {decoded}")
print(f"Match: {text == decoded}")
if __name__ == "__main__":
encode_decode_demo("Hel…How to Escape HTML in Python
This code demonstrates how to use Python's `html.escape` function to safely encode user input for display in HTML, preventing XSS attacks.
import html
def escape_user_input(user_input: str) -> str:
"""Escape HTML-sensitive characters for safe display."""
return html.escape(user_input)
if __name__ == "__main__":
sample_user_input = '<script>alert("XSS")</script> & \'quotes\''
safe_output = escape_user_input(sample_user_input)
print("…How to Filter Text to Only Letters, Numbers, and Spaces in Python
A beginner-friendly function that filters a string to keep only alphabetic characters, digits, and spaces, removing punctuation and symbols.
def filter_text(text, keep_alpha=True, keep_digits=True, keep_spaces=True):
allowed = set()
if keep_alpha:
allowed.update("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
if keep_digits:
allowed.update("0123456789")
if keep_spaces:
allowed.add(" ")
return "".join(ch f…How to Filter a List of Strings by Keyword in Python
A helper function filters a list of strings by a keyword search with optional case sensitivity.
def filter_strings(items, keyword, case_sensitive=False):
"""
Filter a list of strings by a keyword.
Args:
items: list of strings to filter
keyword: substring to search for
case_sensitive: if True, match case exactly
Returns:
list of strings containing the keyw…How to Format a Float as Currency in Python
This code defines a function that converts a float to a string formatted as US currency with two decimal places and comma separators.
def format_currency(amount):
return f"${amount:,.2f}"
if __name__ == "__main__":
test_amounts = [1234.5, 0, 9999999.999, -42.867]
for amount in test_amounts:
print(f"{amount} -> {format_currency(amount)}")How to Generate Text Helper Functions in Python
Three simple Python functions that repeat, join, and count characters in strings for beginners.
def repeat_text(text, times):
"""Repeat a string a given number of times."""
return text * times
def join_words(words, separator=" "):
"""Join a list of words into a single string."""
return separator.join(words)
def count_characters(text):
"""Count character occurrences in a string."""
ret…How to Inspect String Statistics in Python
A beginner-friendly function that returns detailed statistics about a string, including length, word count, character types, and easy text transformations.
def inspect_text(text: str) -> dict:
"""Return useful stats about a string for beginners."""
words = text.split()
return {
"length": len(text),
"word_count": len(words),
"uppercase": sum(1 for ch in text if ch.isupper()),
"lowercase": sum(1 for ch in text if ch.islower()),
…How to Normalize Text in Python
This code defines a function that trims, lowercases, and collapses extra whitespace in a string, returning normalized text.
def normalize_text(text: str) -> str:
normalized = " ".join(text.lower().strip().split())
return normalized
if __name__ == "__main__":
raw = " Hello, WORLD! This is a test. "
print(normalize_text(raw))How to Parse and Clean Text in Python
This code defines three helper functions to parse text into lowercase words, count unique word frequencies, and clean text by removing punctuation and extra whitespace.
def extract_words(text: str) -> list[str]:
"""Return a list of lowercase words from the given text."""
return [word.lower() for word in text.split() if word.isalpha()]
def count_unique_words(text: str) -> dict[str, int]:
"""Return a dictionary with unique words and their frequencies."""
words = extra…How to Partition a String on the First Delimiter in Python
Split a string into a tuple of (before, delimiter, after) at the first occurrence of a given delimiter, using a custom function or the built-in str.partition.
def partition_string(s, delimiter):
"""Split string into (before, delimiter, after) on the first occurrence."""
for i, ch in enumerate(s):
if ch == delimiter:
return s[:i], ch, s[i+1:]
return s, "", ""
if __name__ == "__main__":
# Single-character delimiter
s1 = "hello,world,h…How to Process Text in Python: Normalize Whitespace and Count Words
A beginner-friendly function that normalizes whitespace in a string and counts total and unique words using Python's standard library.
def process_text(text):
"""Basic text processing: normalize whitespace and count words."""
normalized = " ".join(text.split())
word_count = len(normalized.split())
char_count = len(normalized)
# Count unique words
unique_words = set(normalized.lower().split())
unique_count = len(unique…How to Remove Duplicate Adjacent Spaces in Python
This Python function collapses any sequence of two or more adjacent spaces into a single space, preserving all other characters.
def remove_duplicate_adjacent_spaces(text):
"""Replace sequences of 2+ spaces with a single space."""
result = []
prev_was_space = False
for char in text:
if char == " ":
if not prev_was_space:
result.append(char)
prev_was_space = True
else:
…How to Round Numbers with f-strings in Python
Round numbers directly inside f-string expressions using the built-in round() function for clean, readable output formatting.
def main():
# Values to format with expression-based rounding
price = 19.995
tax_rate = 0.0825
distance = 1234.56789
# Round inside the f-string expression using round()
print(f"Price rounded to cents: ${round(price, 2)}")
# Combine rounding with arithmetic inside the expression
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Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.