Python input and output

Output from the Python output python3

The output in Python3 uses the function print (), as shown in the following example:

>>> print(‘hello kitty‘)

Print () can also accept multiple parameters, separated by commas:

>>> print(‘hello‘,‘kitty‘)hello kitty

After you see the string merge output, the middle pattern is separated by commas ~

The print function can receive other data types in addition to receiving strings

>>> print(1)               # 接收整数1>>> print(1+2)           # 表达式3>>> print([1,2,3])       # 列表[1, 2, 3]>>> print({‘a‘:1,‘b‘:2})  # 字典{‘a‘: 1, ‘b‘: 2}

Output in the Python2

The output in Python2 uses print plus the output data, as shown in the following example:

>>> print ‘hello kitty‘

You can also receive multiple parameters:

>>> print ‘1+2 =‘,31+2 = 3

Usage is basically the same as the print () function in Python3 ~

Python formatted output

Formatting the output string

>>> print(‘My name is %s‘ % (‘abc‘))My name is abc

% represents the format operation, and the%s (format character) in the preceding string is replaced with the string ' abc ' after%.

To print an integer:

>>> print("I‘m %d year old" % 18)     # 当只有一个值的时候，可以不适用小括号I‘m 18 year old

Multiple format characters:

>>> print("I‘m %s. I‘m %d year old" % (‘abc‘, 18))I‘m abc. I‘m 18 year old

Multiple format characters can also use dictionaries to pass values:

>>> print("I‘m %(name)s. I‘m %(age)d year old" % {‘name‘:‘abc‘, ‘age‘:18})I‘m abc. I‘m 18 year old

Format character

%s    字符串 (采用str()的显示)%r    字符串 (采用repr()的显示)%c    格式化字符及其ASCII码%b    二进制整数%d    十进制整数%u    格式化无符号整型%o    格式化无符号八进制数%x    格式化无符号十六进制数%X   格式化无符号十六进制数（大写）%e    用科学计数法格式化浮点数%E    作用同%e，用科学计数法格式化浮点数%f     格式化浮点数字，可指定小数点后的精度%g    %f和%e的简写%G    %f 和 %E 的简写%%    字符"%"

?

The format character reserves the location for the real value and controls the format of the display.

The format can be further controlled in the following ways:
%[(name)][flags][width]. [Precision]typecode
(name) is named
Flags can have--, ' or 0. If you do not write the default means right-justified. -Indicates left alignment. ' is a space that fills a space on the left side of a positive number to align with a negative number. 0 means using 0 padding.
Width indicates display widths
Precision indicates the precision after the decimal point

Examples are as follows:

>>> print("%4d" % 5)                 #  flags不填（默认右对齐），width为4（总长为4位）   5>>> print("%-4d" % 5)               #  flags为 - ，表示左对齐5>>> print("%06d" % 5)               # 总长为6位，flags为0，即左边使用0填充000005>>> print(‘-- %f  --‘ % (1.23))       # 格式化浮点数-- 1.230000  -->>> print(‘-- %5.2f  --‘ % (1.2345))     # 总长5位，小数点后保留2位--  1.23  -->>> print(‘-- %05.2f  --‘ % (1.2345))    # 总长5位，小数点后保留2位，flags为0，左边使用0填充（小数点也占一位）-- 01.23  --

There is another format for Python, using format, which is also the official recommended way:

方式一：>>> print("My name is {0}. I‘m {1} year old. Hello {0} !!".format(‘baby‘, 18))My name is baby. I‘m 18 year old. Hello baby !!方式二：>>> print("My name is {name}. I‘m {age} year old. Hello {name} !!".format(name=‘baby‘, age=18))My name is baby. I‘m 18 year old. Hello baby !!

Input in Python input Python3

Input in Python3 uses input () to store the user's input in the terminal into a variable

>>> name=input()hello>>> name‘hello‘

Input () can take a parameter as a hint when the user enters the message, as shown in the following example:

>>> name = input("What is your name?")What is your name?abc>>> name‘abc‘

Tip:input () processes the data entered by the user as a string (str) ~

>>> lst = input()[1,2,3,4,5]>>> type(lst)<class ‘str‘>

Input in the Python2

The Raw_input usage in Python2 is similar to input () in Python3:

>>> age = raw_input("How old are you?")How old are you?12>>> type(age)<type ‘str‘>

Tip:raw_input Also, the data entered by the user is treated as a string (str).

The python2 can also use input () to receive input from the user, where the input () usage differs from the input () in the Python3

>>> name = input("What is your name?")What is your name?baby                                # 这里输入的是 变量 baby，而不是字符串，由于 baby 变量没有定义，所以报错Traceback (most recent call last):  File "<stdin>", line 1, in <module>  File "<string>", line 1, in <module>NameError: name ‘baby‘ is not defined>>> name = input("What is your name?")What is your name?‘baby‘                             # 这里输入的是 字符串 ‘baby‘，成功赋值~>>> lst = input()[1,2,3,4,5]                                                      # 输入的是 列表类型，lst变量即为列表~>>> type(lst)<type ‘list‘>

The input () in Tip:python2 is the type that is entered when it receives the data entered by the user, and why it is stored. Note the difference
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Python input and output