What is the usage of input function in Python?

The "input()" function is an input function that accepts a standard input data and returns the string type. In Python3, the "raw_input()" function is removed, and only the "input()" function is retained, which accepts any arbitrary input, processes all inputs as strings by default, and returns the string type.

1.input() function

In Python3, the input() function accepts a standard input data, Returned as string type.

Note: In Python3, raw_input() and input() are integrated, raw_input() is removed, and only the input() function is retained, which accepts any arbitrary input. Processes all inputs as strings by default and returns the string type.

2.Usage of input() function

The input() function is an input function and an important function to realize human-computer interaction. For example, sometimes the computer will ask you a question You need to answer the question so that the computer can make the next decision. At this time we need to use the input() function.

For example: In an exam, there is a question with four options, of which there is only one correct answer. At this time, you need to answer the option you selected, so that the computer can judge whether you answered the question correctly.

print('请在以下四个选项中【A.1;B.5;C.0;D.2】选出你的选项')
choice=input('请问你的选项是:')
if choice=='A':
    print('恭喜你，回答正确!!!')
else:
    print('很遗憾，回答错误!!!')
 
------------------------------------------------------
 
请在以下四个选项中【A.1;B.5;C.0;D.2】选出你的选项
请问你的选项是:A
恭喜你，回答正确!!!

As you can see from the above, input() is an input function. When you write a question in the brackets of the function, it will print it out in the terminal and wait for your input. After you input, the computer will Judge your answer.

3. Data type of input()

As mentioned at the beginning, in Python3, the input() function accepts a standard input data and returns it as string type. No matter what answer we enter, whether you enter an integer or a string, the input value of the input() function (the collected answer) will always be [mandatorily] converted to the [string] type. (Python3 fixed rules)

choice = input('请输入1或2:')
print(type(choice))
name=input('请输入你的名字:')
print(type(name))
 
----------------------------
 
请输入1或2:1 
<class &#39;str&#39;>
请输入你的名字:张三
<class &#39;str&#39;>

In the first example if choice='A', the input value of input() is converted into a string, and 'A' on the right is also a string type, "=" Both sides are of the same type and run correctly. If it is changed to if choice=A, then an error will occur during operation.

print('请在以下四个选项中【A.1;B.5;C.0;D.2】选出你的选项')
choice=input('请问你的选项是:')
if choice==A:
    print('恭喜你，回答正确!!!')
else:
    print('很遗憾，回答错误!!!')
 
------------------------------------------------------------------------------------------
 
Traceback (most recent call last):
  File "/home/pythonclass/93745296-3f71-4a34-97c4-3acfae4e9d32/3c1401ac-eff9-4b93-89c0-493ca9670e7f/classroom/apps-1-id-5cd9765719bbcf000155479e/98/main.py", line 3, in <module>
    if choice==A:
NameError: name &#39;A&#39; is not defined

4. Forced conversion of the input() function result

choice=input('请选择1或2')
if choice=='1':
    print('正确')
else:
    print('错误')

The above code is very simple, with only two options. If the above code is not two, Rather, there are dozens or hundreds. Should we type '1', '2', '3', '4', '5',...'200', '201'... one by one? ..., at this time we need to find a simpler way, that is, convert all data types into integer types, but didn't it say above that the returns of the input() function are all string types? In fact, it can be forced to convert in some special cases.

choice=int(input('请选择1或2'))
if choice==1:
    print('正确')
else:
    print('错误')
 
------------------------------
 
请选择1或2 1
正确

As long as int() is added before the input() function, the result of the input() function can be forced to be converted into an integer.

So when will we use to force the result to an integer? When the result we want is a number. For example, age, salary, height, weight, etc.

For example: We want to group the students in the class according to their height, then we need to use integers.

height=int(input('请问你的身高是:'))
if 0<height<=150:
    print(&#39;你被分到了1组&#39;)
elif 150<height<=180:
    print(&#39;你被分到了2组&#39;)
else:
    print(&#39;你被分到了3组)
-----------------------------------
请问你的身高是:185   
你被分到了3组

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