Taking User Input in Python
Python is a powerful programming language that allows developers to write code that can interact with users. One of the fundamental tasks of a programmer is to read user input and use that input to execute code.
In Python, there are several ways to take user input. In this article, we will discuss how to take multiple lines of user input and how to read user input until EOF.
Taking Multiple Lines of User Input
Sometimes, the user needs to input multiple lines of text data. In such scenarios, it can be challenging to collect the data in a way that is efficient and practical.
Let’s examine two ways of taking multiple lines of user input in Python. 1.
Using a while loop and the append method
One way to take multiple lines of user input in Python is to use a while loop and the append method. The while loop runs until the user enters a blank line.
The append method is used to add each line of input to a list. Here’s an example:
“`
input_lines = [] # creates an empty list to store user input
while True: # starts an infinite loop
line = input() # takes user input
if not line: # checks if the input is empty and breaks the loop
break
input_lines.append(line) # adds the user input to the list
print(input_lines)
“`
In this example, we create an empty list called input_lines. We then use a while loop to read input lines until the user enters a blank line.
The append method is used to add each input line to the list. Finally, we print the list containing the user input.
2. Using a try/except statement
Another method to take multiple lines of user input is to use a try/except statement.
This approach works by repeatedly reading input lines from the user until the end of file (EOF) is reached. We use a try/except statement to catch the EOFError exception that is raised when the user enters the EOF symbol.
Here’s an example:
“`
input_lines = []
while True: # starts an infinite loop
try:
line = input() # reads input line
input_lines.append(line) # adds the input line to the list
except EOFError: # catches EOFError exception
break # breaks the loop when EOF is reached
print(input_lines)
“`
In this example, we create an empty list called input_lines. We then use a while loop to read input lines until the end of file is reached.
The try/except statement is used to catch the EOFError exception, which indicates that there is no more input left to read. Finally, we print the list containing the user input.
Reading User Input Until EOF
In some cases, a program needs to read user input until the end of file is reached. Python provides two ways to accomplish this task.
1. Using sys.stdin.readlines()
The sys.stdin module provides a file-like object that represents the standard input.
We can use this object’s readlines() method to read all the lines of user input until EOF. Here’s an example:
“`
import sys
input_lines = sys.stdin.readlines()
print(”.join(input_lines))
“`
In this example, we import the sys module and use its stdin attribute to get the standard input file-like object. We then use the readlines() method to read all the lines of user input until EOF.
Finally, we print the concatenated string of all input lines. Note: To signal EOF in the standard input of most operating systems, use either CTRL + D (Unix-based systems) or CTRL + Z (Windows-based systems).
2. Using a try/except statement
Another way to read user input until EOF is to use a try/except statement.
We use a while loop to repeatedly read input lines from the user until the EOFError exception is raised. Here’s an example:
“`
input_lines = [] # creates an empty list to store user input
while True: # starts an infinite loop
try:
line = input() # reads a line of input
input_lines.append(line) # adds the input line to the list
except EOFError: # catches EOFError exception
break # breaks the loop when EOF is reached
print(”.join(input_lines))
“`
In this example, we create an empty list called input_lines.
We then use a while loop to read input lines until the end of file is reached. The try/except statement is used to catch the EOFError exception when there is no more input left to read.
Finally, we print the concatenated string of all input lines.
Conclusion
Python provides multiple ways to take user input. Depending on the specific requirements of your program, you can choose the most suitable method.
You can use a while loop and append method to take multiple lines of user input, while sys.stdin.readlines() or a try/except statement can be used to read user input until EOF. By utilizing the techniques mentioned in this article, you can create interactive Python programs that can engage users and collect data effectively.
In this article, we discussed two ways to take user input in Python: taking multiple lines of input and reading input until EOF. For multiple lines of input, we can use a while loop and the append method or a try/except statement.
To read input until EOF, we can use sys.stdin.readlines() or a try/except statement. It is essential to choose the most appropriate method depending on the specific requirements of the program.
By utilizing the techniques presented in this article, developers can create interactive Python programs that can effectively engage users and collect data.