Master the input of Python's X _7_ data input (built-in function; use of input)

This article will learn python's built-in function input. Before talking about input, we need to introduce what is a built-in function.

1. Built-in functions

• What are built-in functions?
  In python.exe, there are some ready-to-use functions from the start of operation. We call them "built-in functions". The
  print we used before is a built-in function, and its function is to output the content to the console.

• We can use the dir built-in function dir (__builtins__)to view all the built-in functions in python, the following should only be part of it

In [5]: dir (__builtins__)
Out[5]:
['ArithmeticError',
 'AssertionError',
 'AttributeError',
 'BaseException',
 'BlockingIOError',
 'BrokenPipeError',
 'BufferError',
 'BytesWarning',
 'ChildProcessError',
 'ConnectionAbortedError',
 'ConnectionError',
 'ConnectionRefusedError',
 'ConnectionResetError',
 'DeprecationWarning',
 'EOFError',
 'Ellipsis',
 'EnvironmentError',
 'Exception',
 'False',
 'FileExistsError',
 'FileNotFoundError',
 'FloatingPointError',
 'FutureWarning',
 'GeneratorExit',
 'IOError',
 'ImportError',
 'ImportWarning',
 'IndentationError',
 'IndexError',
 'InterruptedError',
 'IsADirectoryError',
 'KeyError',
 'KeyboardInterrupt',
 'LookupError',
 'MemoryError',
 'ModuleNotFoundError',
 'NameError',
 'None',
 'NotADirectoryError',
 'NotImplemented',
 'NotImplementedError',
 'OSError',
 'OverflowError',
 'PendingDeprecationWarning',
 'PermissionError',
 'ProcessLookupError',
 'RecursionError',
 'ReferenceError',
 'ResourceWarning',
 'RuntimeError',
 'RuntimeWarning',
 'StopAsyncIteration',
 'StopIteration',
 'SyntaxError',
 'SyntaxWarning',
 'SystemError',
 'SystemExit',
 'TabError',
 'TimeoutError',
 'True',
 'TypeError',
 'UnboundLocalError',
 'UnicodeDecodeError',
 'UnicodeEncodeError',
 'UnicodeError',
 'UnicodeTranslateError',
 'UnicodeWarning',
 'UserWarning',
 'ValueError',
 'Warning',
 'WindowsError',
 'ZeroDivisionError',
 '__IPYTHON__',
 '__build_class__',
 '__debug__',
 '__doc__',
 '__import__',
 '__loader__',
 '__name__',
 '__package__',
 '__spec__',
 'abs',
 'all',
 'any',
 'ascii',
 'bin',
 'bool',
 'breakpoint',
 'bytearray',
 'bytes',
 'callable',
 'chr',
 'classmethod',
 'compile',
 'complex',
 'copyright',
 'credits',
 'delattr',
 'dict',
 'dir',
 'display',
 'divmod',
 'enumerate',
 'eval',
 'exec',
 'filter',
 'float',
 'format',
 'frozenset',
 'get_ipython',
 'getattr',
 'globals',
 'hasattr',
 'hash',
 'help',
 'hex',
 'id',
 'input',
 'int',
 'isinstance',
 'issubclass',
 'iter',
 'len',
 'license',
 'list',
 'locals',
 'map',
 'max',
 'memoryview',
 'min',
 'next',
 'object',
 'oct',
 'open',
 'ord',
 'pow',
 'print',
 'property',
 'range',
 'repr',
 'reversed',
 'round',
 'set',
 'setattr',
 'slice',
 'sorted',
 'staticmethod',
 'str',
 'sum',
 'super',
 'tuple',
 'type',
 'vars',
 'zip']

2. Built-in function input

printand inputare the first two built-in functions we study

• print: output function, output data to the console
• input: input function, save keyboard input to a variable

Example of use

In [7]: myname=input("请输入你的姓名")
请输入你的姓名123

When the keyboard is entered, the entered content will be stored in the variable myname, and it will be printed below

In [8]: print(myname)
123

With input and output, we can process data more flexibly

The following is what the script runs in VSCode:

name1 =input("请问你的名字是？")
name2 =input("请问你的名字是？")
slogan="{0}，加油，加油"
print(slogan.format(name1))
print(slogan.format(name2))

operation result:

请问你的名字是？张三
请问你的名字是？李四
张三，加油，加油
李四，加油，加油

2. The returned content of input cannot be directly calculated numerically

Please see the following code

In [12]: num1=input("请输入num1")
请输入num1345
In [13]: print(num1*10)
345345345345345345345345345345

In [14]: print(num1+100)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[14], line 1
----> 1 print(num1+100)

TypeError: can only concatenate str (not "int") to str

The reasons for the above are:

• The variable type that input can return is actually a string type
• num1 is a string
• Only digital data supports digital-related operations such as addition, subtraction, multiplication, and division.

In the above code:

num1+100

In fact, it is to add a number 100 to a string. Their types are inconsistent and cannot be calculated. If calculation is required, type conversion will be involved, which will be introduced in the next article.

3. Learning video address: data input input