text = "Hello, World!"
print(len(text))  # 輸出: 13

text = "banana"
print(text.count('a'))  # 輸出: 3

text = "Banana"
print(text.lower().count('a'))  # 輸出: 3

text = "programming is fun"
chars_to_count = ['a', 'm', 'n']
counts = {char: text.count(char) for char in chars_to_count}
print(counts)  # 輸出: {'a': 1, 'm': 2, 'n': 2}

sentence = "This is a sample sentence."
words = sentence.split()
print(len(words))  # 輸出: 5

import re

sentence = "This, is a  sample  sentence! "
words = re.findall(r'\b\w+\b', sentence)
print(len(words))  # 輸出: 5

text = "Python is great. Python is easy. I love Python!"
target_word = "python"
count = re.findall(r'\b' + re.escape(target_word) + r'\b', text.lower()).count(target_word.lower())
# 更簡單的方法：
count = text.lower().split().count(target_word.lower())
print(count)  # 輸出: 3

text = "abracadabra"
substring = "abra"
start = 0
while True:
    pos = text.find(substring, start)
    if pos == -1:
        break
    print(f"Found at position: {pos}")
    start = pos + 1
# 輸出:
# Found at position: 0
# Found at position: 7

from collections import Counter

text = "mississippi"
char_counts = Counter(text)
print(char_counts)
# 輸出: Counter({'i': 4, 's': 4, 'p': 2, 'm': 1})

print(char_counts.most_common(2))  # 輸出: [('i', 4), ('s', 4)]

text = "apple banana apple orange banana apple"
words = text.split()
word_counts = Counter(words)
print(word_counts)
# 輸出: Counter({'apple': 3, 'banana': 2, 'orange': 1})

import re
from collections import Counter

text = "Apple, banana! Apple? Orange; banana: apple."
# 預處理：轉(zhuǎn)換為小寫，去除標點
cleaned_text = re.sub(r'[^\w\s]', '', text.lower())
word_counts = Counter(cleaned_text.split())
print(word_counts)
# 輸出: Counter({'apple': 3, 'banana': 2, 'orange': 1})

import string
from collections import Counter

def letter_frequency(text):
    # 轉(zhuǎn)換為小寫并過濾非字母字符
    letters = [c.lower() for c in text if c.isalpha()]
    return Counter(letters)

text = "Hello, World! This is a sample text."
freq = letter_frequency(text)
print(freq.most_common())
# 輸出類似: [('e', 4), ('l', 3), ('s', 3), ('t', 3), ...]

def file_stats(filename):
    with open(filename, 'r', encoding='utf-8') as file:
        lines = file.readlines()
        num_lines = len(lines)
        num_chars = sum(len(line) for line in lines)
        num_words = sum(len(line.split()) for line in lines)
    return num_lines, num_words, num_chars

lines, words, chars = file_stats('sample.txt')
print(f"Lines: {lines}, Words: {words}, Characters: {chars}")

def count_comments(filename):
    python_comment_patterns = [
        r'^\s*#',  # 行首的注釋
        r'"""[^"]*"""',  # 多行字符串（可能包含注釋）
        r"'''[^']*'''"   # 多行字符串（可能包含注釋）
    ]
    
    with open(filename, 'r', encoding='utf-8') as file:
        content = file.read()
    
    # 更精確的實現(xiàn)需要更復雜的解析
    # 這里簡化處理，僅統(tǒng)計以#開頭的行
    lines = content.splitlines()
    comment_lines = sum(1 for line in lines if line.strip().startswith('#'))
    return comment_lines

comment_count = count_comments('script.py')
print(f"Comment lines: {comment_count}")

import requests
from bs4 import BeautifulSoup
import re

def count_links(url):
    try:
        response = requests.get(url)
        soup = BeautifulSoup(response.text, 'html.parser')
        links = soup.find_all('a', href=True)
        return len(links)
    except Exception as e:
        print(f"Error fetching {url}: {e}")
        return 0

link_count = count_links('https://example.com')
print(f"Links found: {link_count}")

# 不推薦的方式（多次拼接）
result = ""
for char in "abcdef":
    result += char

# 推薦的方式（使用join）
chars = ["a", "b", "c", "d", "e", "f"]
result = "".join(chars)

def count_large_file_words(filename):
    word_count = 0
    with open(filename, 'r', encoding='utf-8') as file:
        for line in file:
            word_count += len(line.split())
    return word_count

# 不推薦的方式（列表查找是O(n)復雜度）
def is_in_list(word, word_list):
    return word in word_list

# 推薦的方式（集合查找是O(1)復雜度）
def is_in_set(word, word_set):
    return word in word_set

text = "café"
print(len(text))  # 輸出: 4（正確統(tǒng)計了é作為一個字符）

# 如果遇到編碼問題，確保以正確的編碼打開文件
with open('file.txt', 'r', encoding='utf-8') as file:
    content = file.read()

def count_overlapping_substrings(text, substring):
    count = 0
    len_sub = len(substring)
    for i in range(len(text) - len_sub + 1):
        if text[i:i+len_sub] == substring:
            count += 1
    return count

text = "abababa"
substring = "aba"
print(count_overlapping_substrings(text, substring))  # 輸出: 3

import re
from collections import Counter

def clean_text(text):
    # 轉(zhuǎn)換為小寫并去除標點
    return re.sub(r'[^\w\s]', '', text.lower())

text = "Hello, World! Hello, Python!"
cleaned = clean_text(text)
word_counts = Counter(cleaned.split())
print(word_counts)
# 輸出: Counter({'hello': 2, 'world': 1, 'python': 1})