2.6 Getting Input from the User

  • Built-in input function requests and obtains user input.
In [1]:
name = input("What's your name? ")
In [2]:
name
Out[2]:
'Paul'
In [3]:
print(name)

Paul
  • If you enter quotes, they’re input as part of the string.
In [4]:
name = input("What's your name? ")
In [5]:
name
Out[5]:
'"Paul"'
In [6]:
print(name)

"Paul"

Function input Always Returns a String

In [7]:
value1 = input('Enter first number: ')
In [8]:
value2 = input('Enter second number: ')
In [9]:
value1 + value2
Out[9]:
'73'
  • Python “adds” the string values '7' and '3', producing the string '73'.
  • Known as string concatenation.

Getting an Integer from the User

  • If you need an integer, convert the string to an integer using the built-in int function.
In [10]:
value = input('Enter an integer: ')
In [11]:
value = int(value)
In [12]:
value
Out[12]:
7
  • Can combine int and input in one statement.
In [13]:
another_value = int(input('Enter another integer: '))
In [14]:
another_value
Out[14]:
3
In [15]:
value + another_value
Out[15]:
10
  • If the string passed to int cannot be converted to an integer, a ValueError occurs.
In [16]:
bad_value = int(input('Enter another integer: '))

------------------------------------------------------------------------
ValueError                             Traceback (most recent call last)
<ipython-input-16-cd36e6cf8911> in <module>
----> 1 bad_value = int(input('Enter another integer: '))

ValueError: invalid literal for int() with base 10: 'hello'
  • Function int also can convert a floating-point value to an integer.
In [17]:
int(10.5)
Out[17]:
10

©1992–2020 by Pearson Education, Inc. All Rights Reserved. This content is based on Chapter 2 of the book Intro to Python for Computer Science and Data Science: Learning to Program with AI, Big Data and the Cloud.

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