# 创建字符串
greeting = "Hello, World!"
print(greeting)

# 示例代码
text = "Hello, World!"

# 字符串长度
length = len(text)
print(length)  # 输出：13

# 字符串拼接
concatenated = text + " Welcome!"
print(concatenated)  # 输出：Hello, World! Welcome!

# 字符串复制
repeated = text * 3
print(repeated)  # 输出：Hello, World!Hello, World!Hello, World!

# 字符串索引
first_char = text[0]
print(first_char)  # 输出：H

# 字符串切片
substring = text[7:12]
print(substring)  # 输出：World

# 大小写转换
lowercase = text.lower()
uppercase = text.upper()
print(lowercase)  # 输出：hello, world!
print(uppercase)  # 输出：HELLO, WORLD!

# 字符串查找
position = text.find("World")
print(position)  # 输出：7

# 字符串替换
replaced = text.replace("World", "Python")
print(replaced)  # 输出：Hello, Python!

# 去除空白
trimmed = "   Hello, World!   ".strip()
print(trimmed)  # 输出：Hello, World!

# 分割字符串
words = text.split(", ")
print(words)  # 输出：['Hello', 'World!']


"""
基础：编写一个Python程序，将字符串 “Python” 转换为全大写并打印出来。
"""
str_1 = "Python"
new_str_1 = str_1.upper()
print(new_str_1)

"""
应用：给定字符串 “Hello, Python!”，使用字符串查找方法找出 “Python” 在该字符串中的位置。
"""
str_2 = "Hello, Python!"
index = str_2.find("Python")
print(index)

"""
挑战：编写一个Python程序，将字符串 “Hello, World!” 中的 “World” 替换为 “Python”，并将结果打印出来。
"""
str_3 = "Hello, World!"
new_str_3 = str_3.replace("World", "Python")
print(new_str_3)