How to Prevent Infinite Loops from Incorrect Data Type Input in C ?

Handling Incorrect Data Type Input in C

Ensuring that the user provides the appropriate data type is crucial for preventing unexpected behavior and infinite loops. In C , handling wrong input can be challenging.

Problem Statement:

When the program expects an integer input and the user enters a character, the program enters an infinite loop. Conversely, the same issue occurs when an integer is expected but a character is entered.

Solution:

The infinite loop occurs because the std::cin function's bad input flag is set when the input fails. To resolve this, we need to:

• Clear the bad input flag: std::cin.clear();
• Discard the invalid input from the buffer: std::cin.ignore(std::numeric_limits<std::streamsize>::max(), 'n');

Here's an example code snippet:

while (std::cout << "Enter a number" && !(std::cin >> num)) {
    std::cin.clear(); // clear bad input flag
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // discard input
    std::cout << "Invalid input; please re-enter.\n";
}

This code loops until the user enters a valid number. It clears the bad input flag, discards the invalid input, and prompts the user to try again.

Alternative Approach:

Instead of using std::cin, you can also get the input as a string and convert it to an integer using std::stoi. This approach allows you to verify the conversion before assigning the input to an integer variable.

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