StringMethods.py

# =============================================
# 문자열 함수(메서드) 예제
# =============================================

# ==================== 대소문자 변환 ====================
print("=== 대소문자 변환 ===")
text = "Hello Python"
print(text.upper())           # HELLO PYTHON
print(text.lower())           # hello python

# ==================== 공백 제거 ====================
print("\n=== 공백 제거 ===")
text = "    Hello, world   "
print(f"[{text.strip()}]")    # [Hello, world]
print(f"[{text.lstrip()}]")   # [Hello, world   ]
print(f"[{text.rstrip()}]")   # [    Hello, world]

# ==================== 치환 ====================
print("\n=== 치환 ===")
text = "Hello, world"
print(text.replace("world", "Python"))  # Hello, Python

# 메서드 체이닝
text = "    Hello, world   "
print(text.upper().strip().replace('H', 'J'))  # JELLO, WORLD

# 실용적 활용: 가격 문자열 처리
price = "21,300원"
result = int(price.replace("원", "").replace(",", "").strip())
print(result)                 # 21300

# ==================== split(), join() ====================
print("\n=== split(), join() ===")

# split()
data = "사과,바나나,파인애플,포도"
fruits = data.split(",")
print(fruits)                 # ['사과', '바나나', '파인애플', '포도']

text = "Hello Python 2024"
words = text.split()
print(words)                  # ['Hello', 'Python', '2024']

# join()
items = ["A", "B", "C", "D"]
result = ",".join(items)
print(result)                 # A,B,C,D

time_parts = ["23", "45", "12"]
print(":".join(time_parts))   # 23:45:12

# ==================== 검색 ====================
print("\n=== 검색 ===")
text = "hello python"

# index()
print(text.index("lo"))       # 3

# find()
print(text.find("xx"))        # -1 (없으면 -1)
print(text.find("python"))    # 6

# count()
text = "aabababbabbaababb"
print(text.count("a"))        # 8

# ==================== startswith(), endswith() ====================
print("\n=== startswith(), endswith() ===")
url = "http://example.com/index.html"

print(url.startswith("http"))   # True
print(url.startswith("https"))  # False
print(url.endswith(".html"))    # True
print(url.endswith(".php"))     # False

# ==================== ord(), chr() ====================
print("\n=== ord(), chr() ===")
print(ord("a"))               # 97
print(ord("A"))               # 65
print(chr(97))                # 'a'
print(chr(65))                # 'A'

# 한글 개수
print(ord("가"))              # 44032
print(ord("힣"))              # 55203
print(ord("힣") - ord("가") + 1)  # 11172

# ==================== String 특성 ====================
print("\n=== String 특성 ===")
text = "hello Python"

# 인덱싱, 슬라이싱 가능
print(text[-4])               # 't'
print(text[::2])              # 'hlopto'
print(text[::-1])             # 'nohtyP olleh'

# in 연산자 (대소문자 구분)
print("P" in text)            # True
print("p" in text)            # False

# immutable - 변경 불가
# text[0] = 'H'  # TypeError

# ==================== 문자 빈도 계산 ====================
print("\n=== 문자 빈도 계산 ===")
word = "Alice in wonderland"
data = word.lower()

# 방법 1: for 문
result = {}
for ch in data:
    if ch.isalpha():
        result[ch] = result.get(ch, 0) + 1
print(result)

# 방법 2: Dict Comprehension
result = {ch: data.count(ch) for ch in data if ch.isalpha()}
print(result)