PythonInput and OutputInput

User Input in Python

User input allows your Python program to interact with the user. You can prompt the user to enter data during program execution using the built-in input() function.

By default, input() returns data as a string — you must explicitly cast it to other types as needed.

Basic Syntax

input_basic.py
name = input("Enter your name: ")
print("Hello,", name)
output.txt
Enter your name: Alice
Hello, Alice

Explanation:

  • input(prompt) displays the prompt message.
  • The function returns the user input as a string.

Example 1: Input as Integer

input_int.py
age = int(input("Enter your age: "))
print("You are", age, "years old.")
output.txt
Enter your age: 25
You are 25 years old.

Explanation:

  • Input is cast to integer using int().
  • If the input is not a valid number, an error occurs.

Example 2: Input as Float

input_float.py
temperature = float(input("Enter temperature in Celsius: "))
print("Temperature is", temperature, "°C")
output.txt
Enter temperature in Celsius: 36.6
Temperature is 36.6 °C

Explanation:

  • Input is cast to float using float() for decimal values.

Example 3: Input as Boolean

input_bool.py
value = input("Enter True or False: ")
bool_value = value.lower() == "true"
print("Boolean value:", bool_value)
output.txt
Enter True or False: True
Boolean value: True

Explanation:

  • Since input() returns a string, we convert the string to lowercase and compare to "true" to simulate boolean input.

Example 4: Input as List (from String)

input_list.py
numbers = input("Enter numbers separated by spaces: ")
num_list = numbers.split()
print("List of numbers:", num_list)
output.txt
Enter numbers separated by spaces: 1 2 3 4 5
List of numbers: ['1', '2', '3', '4', '5']

Explanation:

  • The split() method splits the input string into a list of strings.
  • You can convert each to an integer using list comprehension.

Example 5: Input as List of Integers

input_list_int.py
numbers = input("Enter numbers separated by spaces: ")
num_list = [int(num) for num in numbers.split()]
print("List of integers:", num_list)
output.txt
Enter numbers separated by spaces: 10 20 30
List of integers: [10, 20, 30]

Explanation:

  • List comprehension is used to convert each string to an integer.

Example 6: Input as Tuple

input_tuple.py
values = input("Enter values separated by commas: ")
tup = tuple(values.split(","))
print("Tuple:", tup)
output.txt
Enter values separated by commas: a,b,c
Tuple: ('a', 'b', 'c')

Explanation:

  • The input string is split on commas and converted into a tuple.

Example 7: Input as Set

input_set.py
values = input("Enter unique values separated by spaces: ")
value_set = set(values.split())
print("Set:", value_set)
output.txt
Enter unique values separated by spaces: apple banana apple orange
Set: {'banana', 'orange', 'apple'}

Explanation:

  • The input string is split and converted to a set to remove duplicates.

Summary

  • The input() function always returns a string.
  • Use type casting (int(), float(), bool(), list(), etc.) to convert input to desired data type.
  • For collections (list, tuple, set), use split() and comprehensions to process the input.
Special Data typeOutput