Why Does `cin` Cause an Infinite Loop with Non-Numerical Input?

Infinite Loop with cin when Expecting Numerical Input with Character Input

The code in question involves an infinite loop with cin when characters are input instead of expected numbers.

Explanation of Infinite Loop

When cin encounters non-numeric input, it enters the fail state and stops prompting the command line for further input. This causes the loop to continue running without any user interaction.

Detecting Invalid Input with cin

To avoid this problem and detect invalid input, you can check if cin is in the fail state using:

if (cin.fail())
{
    // Handle invalid input here
}

If the fail state is encountered, you can clear it and discard the bad input using:

cin.clear();
cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

This resets cin to a working state, allowing you to continue prompting for input.

For more sophisticated validation, you can use a string input stream to check the input character by character and perform more advanced validation.

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