How to enter variables in python

Now, you can use print() to output the results you want. But what if you want the user to enter some characters from the computer?

Python provides an input() that allows users to enter a string and store it in a variable. For example, enter the user's name: (Recommended learning: Python video tutorial)

>>> name = input()
Michael

When you enter name = input() and press Enter, Python interacts The command line is waiting for your input. At this time, you can enter any characters and press Enter to complete the input.

After the input is completed, there will be no prompts, and the Python interactive command line returns to the >>> state. So where did the content we just entered go? The answer is stored in the name variable. You can directly enter name to view the variable content:

>>> name
'Michael'

What is a variable?

Please recall the basic algebra knowledge learned in junior high school mathematics:

Suppose the side length of the square is a, then the area of ​​the square is a x a. Treating the side length a as a variable, we can calculate the area of ​​the square based on the value of a, for example:

If a=2, the area is a x a = 2 x 2 = 4;

If a=3.5, then the area is a x a = 3.5 x 3.5 = 12.25.

In computer programs, variables can not only be integers or floating point numbers, but also strings. Therefore, name as a variable is a string.

To print out the contents of the name variable, in addition to writing name directly and pressing Enter, you can also use the print() function:

>>> print(name)
Michael

With input and output, we can The program that printed 'hello, world' for the first time has been changed into a meaningful program:

name = input()
print('hello,', name)

Run the above program. The first line of code will let the user enter any character as his or her name, and then store it in the name variable. ; The second line of code will say hello to the user based on the user's name, for example, enter Michael:

C:\Workspace> python hello.py
Michael
hello, Michael

But when the program is running, there is no prompt message telling the user: "Hey, enter your name quickly", so Seems very unfriendly. Fortunately, input() allows you to display a string to prompt the user, so we changed the code to:

name = input('please enter your name: ')
print('hello,', name)

Run this program again, you will find that as soon as the program is run, please enter your will be printed first name:, in this way, the user can follow the prompts and enter the name, and get the output of hello, xxx:

C:\Workspace> python hello.py
please enter your name: Michael
hello, Michael

Each time the program is run, the output results will be different depending on the user's input.

Under the command line, input and output are so simple.

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