1.1输入

? ? ? ? 我们说input()函数直接获取信息，究竟有什么意义呢？意思就是，用户输入的任何内容都将按照它实际的内容保存，并且Python将尝试为为输出的内容匹配正确的数据类型。如果用户输人5，那么这个数将值保存为整数。如果用户输入5.0，该值将保存为浮点数。

? ? ? ? 如下：

? ? ? ? ? ? ? ? 输入：

a = input()
b = input()
print(a, b)

????????????????输出：

5
5.0
5 5.0

Process finished with exit code 0

但是，解释器读到的一定是字符串类型的，如果你想要使用其他数据类型，需要类型转换。

?类型转换：

num = input()
print(num, type(num))
num1 = int(num)
print(num==5)
print(num1==5)

运行：

5
5 <class 'str'>
False
True

Process finished with exit code 0

1.2输出

? ? ? ? 很多时候，我们想把一个（或多个）变量中的值放到一个更大的字符串中。我们知道可以把字符串连接起来成为一个新的字符串。当字符串变的较长的时候，这可能变的难以处理，并且如果我们忘记在变量周围添加一些额外的空格，这很容易其格式化输出很难看。

我们Ctrl+鼠标右键点击print后可以看到：

print(*args, sep=' ', end='\n', file)
*args: arguments 参数
sep: separator 分隔符,?用来间隔多个对象。
end: end 结尾,用来设定以什么结尾。默认值是换行符 \n，我们可以换成其他字符。
file:要写入的文件对象。


print("Hello World")  #字符串类型可以直接输出
 
---------------------------------------------
运行结果如下：
Hello World
-----------------------------------------------
 
a=1
b="Hello World"
print(a, b)  #可以一次输出多个对象，对象之间用逗号分隔
------------------------------------------------
运行结果如下：
1 Hello World
-------------------------------------------------
 
#如果直接输出字符串，而不是用对象表示的话，可以不使用逗号
print("sun""haoyu")
print("sun","haoyu")
 
--------------------------------------------------
运行结果如下：
sunhaoyu
sun haoyu
可知，不添加逗号分隔符，字符串之间没有间隔
-----------------------------------------------------
 
print("www", "baidu", "com", sep=".")  # 设置间隔符
----------------------------------------------------
运行结果如下：
www.snh48.com

file的引用：

?1.2.1格式化输出

老的格式化：占位符
%d: digit 整型
%f: float 浮点型
%s: string 字符串

data = 1
data2 = 2.2
data3 = "123"
print(data, data2, data3)
print("data is %d, data2 is %f, data3 is %s" % (data, data2, data3))
#限制显示的宽度: %numd  %nums
data = 9999
print("data is %4d, data2 is %.1f, data3 is %6s" % (data, data2, data3))
data = 1
print("data is %4d, data2 is %.1f, data3 is %6s" % (data, data2, data3))

#左对齐：-
print("data is %-4d, data2 is %.1f, data3 is %-6s" % (data, data2, data3))

#右对齐：+
print("data is %+4d, data2 is %.1f, data3 is %+6s" % (data, data2, data3))

输出：

1 2.2 123
data is 1, data2 is 2.200000, data3 is 123
data is 9999, data2 is 2.2, data3 is    123
data is    1, data2 is 2.2, data3 is    123
data is 1   , data2 is 2.2, data3 is 123   
data is   +1, data2 is 2.2, data3 is    123

Process finished with exit code 0

新的格式化：format
f/F"{variable_name}"
{variable_name:宽度}

data = 1
data2 = 2.2
data3 = "123"
print(f"data is {data}, data2 is {data2}, data3 is {data3}")
print(F"data is {data:4}, data2 is {data2}, data3 is {data3}")
data = 9999
print(f"data is {data:4}, data2 is {data2}, data3 is {data3}")
#左对齐: <
data = 1
print(f"data is {data:<4}, data2 is {data2}, data3 is {data3}")
#右对齐: >
print(f"data is {data:>4}, data2 is {data2}, data3 is {data3}")
#居中对齐: ^
print(f"data is {data:^4}, data2 is {data2}, data3 is {data3}")
# 填充： *
print(f"data is {data:*^4}, data2 is {data2}, data3 is {data3}")

输出：

1 2.2 123
data is 1, data2 is 2.2, data3 is 123
data is    1, data2 is 2.2, data3 is 123
data is 9999, data2 is 2.2, data3 is 123
data is 1   , data2 is 2.2, data3 is 123
data is    1, data2 is 2.2, data3 is 123
data is  1  , data2 is 2.2, data3 is 123
data is *1**, data2 is 2.2, data3 is 123

Process finished with exit code 0