How to Prevent Infinite Loops When Handling Erroneous Data Type Input in C ?

How to Tackle Erroneous Data Type Input

In C , addressing invalid input is crucial to maintain program integrity. For instance, when requesting an integer and encountering a character input, the program should gracefully handle the error and solicit the correct input again. However, encountering input of an unexpected type can lead to infinite loops.

Reason for Infinite Loop

The infinite loop arises because the input stream's "bad input" flag is set when the expected input is not received. The bad input flag must be manually cleared, and the incorrect input discarded from the stream buffer.

Solution Using Input Validation

To prevent the infinite loop, employ the following approach:

// Loop if input fails (e.g., no characters were read)
while (std::cout << "Enter a number" && !(std::cin >> num)) {
    std::cin.clear(); // Clear the bad input flag
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // Discard the input
    std::cout << "Invalid input; please re-enter.\n";
}

Alternative Input Approach

Instead of using input validation, you can obtain the input as a string and then try to convert it to an integer using std::stoi or a similar method that provides conversion status checks.

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