O Store the Words Given as Input. Again
Python Beginner
A Complete Guide to User Input in Python
Learning about the Python input part in detail along with its many use-cases
User input is disquisitional for building interactive programs. Every programming language has its unique implementation of an input interface. C++ has scanf, Java has the Scanner grade, and Ruby has gets.
While in most cases, this input stems from the keyboard, other forms similar mouse clicks, track-pad, sensors, etc. are also possible.
As always, Python provides a simple framework for getting user input in the grade of the input() function.
The input role reads a line from the console, converts it into a string, and returns information technology.
In this tutorial, we will encompass the input() function in detail using a diverseness of use-cases. We volition talk over the several forms in which input can exist and how to parse this input into our required format with the assist of code snippets.
Syntax
input([prompt])
Hither,
prompt: an optional cord argument, used to brandish a message for the user. Example: 'Enter Name:'
When the input() function is called, the program flow halts until the user enters some input. The user then adds some information and presses the Enter cardinal. The input function returns to the program with the entered string.
entered_value = input('Enter some value: ')
print(entered_value) Output:
Input Blazon
The input function converts all information that information technology receives into the string format. Let us take a look:
Output:
Enter name: Chaitanya Baweja
Enter age: xx
data_type of name: <grade 'str'>
data_type of age: <class 'str'> We used the type office to check the object's data type. As you lot can see above, it does not matter whether we enter a number or a character string. Both of them return equally string objects.
Take an integer input from the user
As input() role returns everything as a string, we demand to perform some explicit type-conversion for accepting integers. Here, we volition use the int() function.
Output:
Enter start num: x
Enter second num: 5
Type of num_1: <grade 'int'>
Blazon of num_2: <class 'int'>
The sum of given numbers is : 15
int(cord)converts the given string to an integer type.
Accept a float input from the user
Similarly, we can get a float value using the float() function.
Output:
Enter value: 5.6
Blazon of float_1: <course 'float'>
Twice the given numbers is : xi.2 User Input Exception Handling
A common event with blazon-conversion is the ValueError exception.
When the user enters input that cannot be converted into the given type, nosotros become a ValueError exception.
For example, the user enters a random string for historic period.
num = int(input('Enter age: ')) Here, the int() function expects an integer value wrapped inside a string. Any other type of value volition event in an mistake. Await what happens when nosotros enter 'nope' as input.
Output:
Enter age: nope ---------------------------------------------------------
ValueError Traceback (most recent call terminal)
<ipython-input-x-1fa1cb611d10> in <module>
----> 1 num_1 = int(input('Enter age: '))ValueError: invalid literal for int() with base 10: 'nope'
To ensure that the user enters valid information, nosotros need to handle many such errors that unremarkably occur with user input. We will use Python Exception Handling for this purpose. Take a wait:
Over again if we enter 'nope' as input:
Enter a number: nope
This is not a number. In the above snippet, if the user enters a not-integer input, the code will heighten an exception. This exception is defenseless past the except statement where we print: 'This is not a number'.
Considering of this try-except block, our plan will not crash on wrong user input.
Nosotros can apply the exception block along with a loop. Thus, the user will exist prompted again and again until they provide valid input.
Multiple input values in a unmarried line
We tin can besides ask for multiple values directly on a single line with simply i call to the input() function. For case, permit'southward get some data about a student from the user and shop information technology in different variables.
Output:
Enter pupil's name, age and score separated by space:Chaitanya 20 100
Educatee Name: Chaitanya
Student Historic period: 20
Student Score: 100 Here, we separated the input string by spaces using the split() method.
Get a list of numbers as input
But what happens when you are non aware of the number of input values?
Let u.s.a. suppose that you lot demand to enter a list of numbers and render their sum. You are not aware of the number of elements in that list.How do we input this list?
We use both the separate and the map function. The carve up() method will divide the entered string into a list of strings. So, the map() function will perform the int operation on all the listing elements.
Output:
Enter a listing of numbers separated by space: ten 20 30 40 50 sixty
Intermediate_list: ['ten', '20', '30', '40', '50', '60']
Number List: [10, 20, thirty, 40, 50, sixty]
List sum: 210 In the lawmaking above:
-
input()returns a string containing numbers separated past spaces. -
split()returns a list of strings partitioned on the spaces. -
map()performsint()performance on all the listing elements and returns a map object. -
list()function converts the map object dorsum into a listing.
Multi-Line input from a user
The input() function returns whenever information technology encounters a newline character (when the user presses Enter central). Thus, if y'all try to ship multi-line information, input() will only return the first line.
To overcome this, we can use for-loop. We get i line of input per iteration and stop when we receive an empty line ('Press Enter on an empty line'). We combine all these lines in a list.
Output:
Conclusion
Python provides a simple framework for getting user input. The input role reads a line from the console, converts it into a string, and returns it.
The input function converts all data that it receives into the string format. Nosotros use type-conversion to convert the input into the required format.
Exceptions occurring due to invalid input tin be managed using the endeavor-except block. The split and map functions help input multiple values in the aforementioned line.
Chaitanya Baweja aspires to solve real world problems with engineering solutions. Follow his journey on Twitter and Linkedin.
Source: https://towardsdatascience.com/a-complete-guide-to-user-input-in-python-727561fc16e1
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