Python字符串操作

name = '张三'
city = "北京"
message = 'Hello World'

text = "Python编程"

print(text[0])    # 输出：P
print(text[1])    # 输出：y
print(text[0:6])  # 输出：Python
print(text[6:])   # 输出：编程

text = "Hello"
print(text[-1])   # 输出：o
print(text[-2])   # 输出：l

original = "Hello World"
new_string = original[:6] + "Python"
print(new_string)  # 输出：Hello Python

print('这是单引号：\'')      # 输出：这是单引号：'
print("这是双引号：\"")      # 输出：这是双引号："
print("第一行\n第二行")     # 输出两行文字
print("姓名\t年龄")         # 输出：姓名    年龄

print(r"换行符：\n")  # 输出：换行符：\n
print(r"路径：C:\new folder")  # 输出：路径：C:\new folder

str1 = "Hello"
str2 = "Python"

print(str1 + str2)   # 连接：HelloPython
print(str1 * 3)      # 重复：HelloHelloHello
print('H' in str1)   # 检查包含：True
print('h' in str1)   # 检查包含：False

name = "小明"
age = 12
print("我叫%s，今年%d岁" % (name, age))

name = "小红"
score = 95.5
print("{}的成绩是{:.1f}分".format(name, score))

name = "小刚"
age = 15
print(f"{name}今年{age}岁")

# 还可以进行计算
a = 5
b = 3
print(f"{a} + {b} = {a + b}")  # 输出：5 + 3 = 8

letter = """
亲爱的用户：

    欢迎使用我们的服务。
    如有问题，请联系客服。

    此致
敬礼！
"""
print(letter)

text = "hello world"

# 大小写转换
print(text.upper())        # HELLO WORLD
print(text.capitalize())   # Hello world

# 查找和替换
print(text.find("world"))  # 6
print(text.replace("world", "Python"))  # hello Python

# 去除空格
text_with_spaces = "   hello   "
print(text_with_spaces.strip())  # hello

# 分割字符串
sentence = "苹果,香蕉,橙子"
fruits = sentence.split(",")
print(fruits)  # ['苹果', '香蕉', '橙子']

# 检查字符串特性
print("hello".isalpha())    # True，全是字母
print("123".isdigit())      # True，全是数字
print("abc123".isalnum())   # True，字母或数字

# 对齐文本
print("标题".center(20, "="))  # =========标题=========

# 统计出现次数
text = "apple banana apple"
print(text.count("apple"))  # 2

# 检查开头和结尾
filename = "document.pdf"
print(filename.endswith(".pdf"))  # True

# 处理用户输入
username = input("请输入用户名：").strip()
if len(username) < 3:
    print("用户名太短")
else:
    print(f"欢迎，{username}！")

# 文件路径处理
path = r"C:\Users\Documents\file.txt"
filename = path.split("\\")[-1]
print(f"文件名：{filename}")

# 生成报告
students = ["张三", "李四", "王五"]
scores = [85, 92, 78]

report = "成绩报告：\n"
for name, score in zip(students, scores):
    report += f"{name:5}：{score:3}分\n"

print(report)

text = "你好，世界"
encoded = text.encode("utf-8")  # 转换为字节
decoded = encoded.decode("utf-8")  # 转换回字符串
print(decoded)  # 你好，世界