Add string demo

0002_3/string.py

@@ -0,0 +1,70 @@
+# 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)