How to Reliably Validate Double Input in C ?

Validating User Input as a Double in C

Validating user input to ensure its integrity is crucial in C programming. When dealing with floating-point values, it becomes essential to verify that the input is indeed a double.

Consider the following code snippet that iteratively prompts the user for a double:

double x;

while (1) {
    cout << '>';
    if (cin >> x) {
        // valid number
        break;
    } else {
        // not a valid number
        cout << "Invalid Input! Please input a numerical value." << endl;
    }
}

However, the provided code contains a flaw: if the user enters an invalid input, the if statement will fail and the else block will display an error message. However, the program will not prompt the user for input again, resulting in an infinite loop of error messages.

To resolve this issue, we can utilize the cin.clear() function to clear the error state and the while (cin.get() != 'n') ; loop to empty the input buffer. This way, when an invalid input is encountered, the program will display the error message, clear the error state, discard the invalid input, and prompt the user for a valid input.

The above is the detailed content of How to Reliably Validate Double Input in C ?. For more information, please follow other related articles on the PHP Chinese website!