One of the most fundamental features of any programming language is the ability to accept input from the user and use it in our program. In Python, this is done using the built-in “input()”function. In this tutorial, we will learn how to take user input in Python and how to use it in our program.
The “input()” function:
The “input()” function is used to accept user input in Python. It reads a line of text from the standard input (usually the keyboard) and returns it as a string. Here is an example of how to use the “input()” function:
name = input("Enter your name: ") print("Hello, " + name)
In this example, we prompt the user to enter their name and store it in the “name” variable. We then use the print() function to print a greeting using the user’s name.
Converting user input to a different data type:
By default, the “input()” function returns a string. However, we may need to use the user’s input in a different data type, such as an integer or a floating-point number. To do this, we can use Python’s built-in type conversion functions. Here is an example of how to convert user input to an integer:
age = input("Enter your age: ") age = int(age) # Convert the age to an integer if age < 18: print("You are a minor.") else: print("You are an adult.")
In this example, we prompt the user to enter their age and store it in the “age” variable as a string. We then use the “int()” function to convert the age to an integer and store it back in the “age” variable. We can then use an “if” statement to check the age and print a message accordingly.
We can use similar techniques to convert user input to other data types, such as floating-point numbers (using the float() function) or Booleans (using the bool() function).
Validating user input:
It is important to validate user input to make sure it is in the correct format and falls within the expected range. For example, if we are expecting the user to enter an integer, we should make sure that the input is indeed an integer before attempting to use it in our program.
To validate user input, we can use Python’s built-in “try”and “except” statements. Here is an example of how to validate user input to make sure it is an integer:
while True: try: num = int(input("Enter a number: ")) break # Input is valid, exit the loop except ValueError: print("Invalid input. Please try again.")
In this example, we use a “while” loop to continuously prompt the user for input until they enter a valid integer. We use a “try” block to try converting the user’s input to an integer using the “int()” function. If the conversion is successful, we exit the loop using the “break” statement. If the conversion fails, we catch the “ValueError” exception and print an error message to the user.