How to Use a Loop in C+ + to Get Valid User Input Between 4 and 20

Learn how to effectively prompt users for valid input in C+ + using loops to ensure they enter a number between `4 and 20`.
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Mastering Input Validation in C+ + with Loops

When programming, one of the key tasks is to collect valid input from users. A common requirement is to ensure that the input number falls within a specified range. In this guide, we will discuss how to repeatedly ask users for input until they provide a valid number, specifically within the range of 4 to 20. This approach enhances user experience by avoiding invalid entries and ensures your program runs smoothly.

The Problem

In C+ + , we often need to ask users for input. However, if we don’t ensure that the input falls within an acceptable range, the program might behave unexpectedly. For example, imagine if we needed the users to select the number of sides on a die. If they entered an invalid number, like 2 or 23, our program should prompt them again until a correct number is provided.

Example Scenario

The user should input a number representing the sides of a die, which should only be between 4 and 20. If they enter a value outside this range, the program should prompt them again.

The Solution: Using a Loop for Input Validation

Step-by-Step Guide

To solve this issue, we can utilize a while loop. Here's how the solution is structured:

Infinite Loop: We set up a loop that will run indefinitely until it breaks upon receiving valid input.

Prompt for Input: Inside the loop, we prompt the user to enter a number between 4 and 20.

Input Validation: We check if the input number is within the valid range. If it is, we can proceed with our program; if not, we prompt the user again.

Implementation

Here’s how you can implement this logic in C+ + :

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Imports and Namespace: We import necessary libraries and utilize the standard namespace.

Randomness: The srand(time(0)) is used to seed the random number generator so that the rolls are different each time the program runs.

User Input: The program prompts the user for input, and we check the validity of that input using the conditional statement.

Loop Mechanism: The loop continues until a correct input is entered (4 <= num <= 20).

Feedback: If the input is invalid, the user is informed and prompted to try again.

Conclusion

Using loops for input validation is a fundamental skill in programming that ensures your applications behave as intended. By implementing the above C+ + code, you can reliably prompt users for valid input and enhance the overall user experience within your programs.

Feel free to adapt this concept to suit your specific needs, whether you're creating games, interactive applications, or any software that requires user input!

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