Python 字符串应用实例，至少10个

1. 字符串加密解密

# 加密
def encrypt(s):
    result = ""
    for c in s:
        result += chr(ord(c) + 1)
    return result

# 解密
def decrypt(s):
    result = ""
    for c in s:
        result += chr(ord(c) - 1)
    return result

text = "Hello World"
encrypted = encrypt(text)
print(encrypted)  # Ifmmp!Xpsme
decrypted = decrypt(encrypted)
print(decrypted)  # Hello World

2. 字符串去重

def remove_duplicates(s):
    result = ""
    for c in s:
        if c not in result:
            result += c
    return result

text = "Hello World"
result = remove_duplicates(text)
print(result)  # Helo Wrd

3. 字符串反转

def reverse(s):
    result = ""
    for i in range(len(s)-1, -1, -1):
        result += s[i]
    return result

text = "Hello World"
result = reverse(text)
print(result)  # dlroW olleH

4. 判断字符串是否为回文

def is_palindrome(s):
    return s == s[::-1]

text = "racecar"
result = is_palindrome(text)
print(result)  # True

5. 统计字符串中出现次数最多的字符

def most_common(s):
    count = {}
    for c in s:
        if c in count:
            count[c] += 1
        else:
            count[c] = 1
    return max(count, key=count.get)

text = "Hello World"
result = most_common(text)
print(result)  # l

6. 模糊匹配字符串

def fuzzy_match(s1, s2):
    n1, n2 = len(s1), len(s2)
    if n1 > n2:
        s1, s2 = s2, s1
        n1, n2 = n2, n1
    for i in range(n2 - n1 + 1):
        if all(s1[j] == s2[i+j] or s1[j] == "?" for j in range(n1)):
            return True
    return False

text = "Hello World"
pattern = "H?llo*"
result = fuzzy_match(pattern, text)
print(result)  # True

7. 计算字符串的哈希值

def string_hash(s):
    p, m = 31, 10**9+9
    h = 0
    for c in s:
        h = (h * p + ord(c)) % m
    return h

text = "Hello World"
result = string_hash(text)
print(result)  # 550055981

8. 字符串排序

def sort_string(s):
    return "".join(sorted(s))

text = "Hello World"
result = sort_string(text)
print(result)  # !HWdellloor

9. 字符串压缩

def compress(s):
    result = ""
    count = 1
    for i in range(1, len(s)):
        if s[i] == s[i-1]:
            count += 1
        else:
            result += s[i-1] + str(count)
            count = 1
    result += s[-1] + str(count)
    return result

text = "aaabbcc"
result = compress(text)
print(result)  # a3b2c2

10. 字符串模板替换

from string import Template

template = Template("$name is $age years old.")
result = template.substitute(name="Tom", age=20)
print(result)  # Tom is 20 years old.