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Rahul Gupta
Rahul Gupta

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Day 38/100: Advanced input() Handling in Python

#python #programming #learning #100daysofcode

By now, you're familiar with Python's input() function. But today, we’ll take it up a notch and learn how to make it smarter, safer, and more user-friendly.

Let’s explore:

  • Type conversion
  • Error handling
  • Custom prompts
  • Looping until valid input
  • Handling lists, multiple values, and booleans

🧠 The Basics of input() 

name = input("Enter your name: ") print(f"Hello, {name}!")
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But here’s the catch — input() always returns a string.
So for numbers and other types, you must convert it manually.

🔁 Converting Input to Numbers 

age = int(input("Enter your age: ")) print(f"You will be {age + 1} next year.")
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If the user enters something invalid (like "hello"), this throws an error.

🛡️ Safe Input with try-except

Let’s make it safer:

try: age = int(input("Enter your age: ")) print(f"You entered: {age}") except ValueError: print("That's not a valid number!")
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🔄 Loop Until Valid Input

Use a loop to ask repeatedly until correct input is given:

while True: user_input = input("Enter a number: ") try: number = float(user_input) break except ValueError: print("Please enter a valid number!")
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🔢 Getting Multiple Inputs

Split input with .split():

data = input("Enter your name and age (e.g., John 25): ") name, age = data.split() print(f"Name: {name}, Age: {age}")
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To convert age:

age = int(age)
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Or using list comprehension:

nums = input("Enter 3 numbers separated by space: ") numbers = [int(x) for x in nums.split()] print(numbers)
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✅ Accepting Boolean Input

For yes/no or true/false, use .lower() and compare:

ans = input("Do you agree? (yes/no): ").strip().lower() if ans in ["yes", "y"]: print("Agreed!") elif ans in ["no", "n"]: print("Not agreed.") else: print("Invalid response.")
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🛠️ Creating Custom Input Functions

You can wrap all of this in reusable functions:

def get_int(prompt): while True: try: return int(input(prompt)) except ValueError: print("Please enter a valid integer.") age = get_int("Enter your age: ") print(age)
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📦 Parsing JSON from Input 

import json data = input("Enter JSON: ") try: obj = json.loads(data) print("Parsed:", obj) except json.JSONDecodeError: print("Invalid JSON")
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🧪 Extra: Input with Defaults

Python doesn't natively support defaults with input(), but you can simulate:

def input_with_default(prompt, default="yes"): user_input = input(f"{prompt} [{default}]: ") return user_input.strip() or default response = input_with_default("Continue?") print(response)
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🧾 Summary

Task Solution Example
Basic input input("Enter name: ")
Convert to number int(input(...))
Safe input (try-except) Use try-except for validation
Loop until valid while True with break
Split multiple inputs input().split()
List of values [int(x) for x in input().split()]
Boolean input Check for "yes"/"no" variants
JSON parsing Use json.loads()
Input with default fallback Simulate with string check

✅ TL;DR

  • input() always returns strings — convert and validate!
  • Wrap your logic in reusable functions for cleaner code.
  • Use loops + try-except for bulletproof input handling.
  • Make your scripts interactive and user-proof.

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