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Python学习day05 - Python基础（3）

Python学习day05 - Python基础（3）1. 格式化输出的三种方式 1.1 占位符 1.2 format格式化 1.3 f-String格式化 2. 基本运算符 2.1 算术运算符 2.2 比较运算符 2.3 赋值运算符 2.4 逻辑运算符 2.5 身份运算符 2.6 Python运算符的优先级 3. 流程控制之if判断 3.1 语法 3.2 if的嵌套 Tips：

1. 格式化输出的三种方式

首先我们要明白格式化输出是什么意思，格式化大家都懂，比如把硬盘格式化掉，里面的东西全都清空，但是格式化输出不太一样，格式化输出大概就是按照某种规范，某种格式来输出一些数据，这种规范或者格式就叫做格式化。

1.1 占位符

占位符常用%s和%d，%s是针对所有数据类型，%d仅仅针对数字类型，所以其实我们只需要用%s就可以了。

例如：
xxxxxxxxxx

3

1

name = 'dog'

2

age = 1

3

print('my name is %s my age is %s' % (name, age))
my name is dog my age is 1

可以看到上述举例中%s可以替代数字和字符串型数据

1.2 format格式化

出现较晚但比较鸡肋的一种格式化方法

例如：
xxxxxxxxxx

3

1

name = 'LOL'

2

age = 7

3

print("Hello, {1}. You are {0} years old.".format(age, name))
Hello，LoL，you are 7 years old

上述输出双引号里大括号里内容即为后面format里面的索引号。

1.3 f-String格式化

迄今为止最实用的一种格式化输出的方法

例如：
xxxxxxxxxx

3

1

name = "DNF"

2

age = 11

3

print(f"Hello, {name}. You are {age} years old.")
Hello,DNF,You are 11 years old

上述大写的F也同样适用，另外可以在输出结果后面精确至某几位。

例如：
xxxxxxxxxx

2

1

hi = 6.6666

2

print(f'{hi:.2f}')
6.67

f-string的格式控制方法如下图

{<参数序号>:<格式控制标记>}