python 中字符串的用法

Python中的字符串可以使用单引号、双引号、三引号来定义，例如：

str1 = 'hello world'
str2 = "hello world"
str3 = '''hello 
world'''

字符串也支持拼接、切片、替换、查找等操作，例如：

str1 = "hello"
str2 = "world"
print(str1 + " " + str2) # 拼接

str = "hello world"
print(str[0]) # 切片
print(str[2:5])

str = "hello world"
print(str.replace("world", "python")) # 替换

str = "hello world"
if "world" in str: # 查找
    print("Yes")
else:
    print("No")

同时，Python中字符串还支持格式化输出，例如：

name = "John"
age = 28
print("My name is %s, and I am %d years old." % (name, age))

输出结果为：`My name is John, and I am 28 years old.`