course = 'Welcome to Python'

# len() 字符串的字符数
print(len(course))

# 大写
print(course.upper())

# 小写
print(course.lower())

# 打印字符位置,大小写敏感
print(course.find('W'))

# 替换
print(course.replace('Python', 'Python World'))

print(course)