字符比较始终为假c

Question

I'm trying to do a simple do while loop where any letter other than 'y' or 'n' is invalid and the loop is repeated. Does anyone know why this loop always evaluates to false? Even when a valid character is entered?

char user_response[2];

do {
    printf("\nDo you want to process another range (y or n): ");
    scanf("%1s", user_response);
    user_response[0] = tolower(user_response[0]);
}
while (user_response[0] != 'y' || user_response[0] != 'n');

return user_response[0];

Answer 1

You should change || to &&.

Answer 2

You want to use "&&" (and) instead of "||" (or).

You have two tests here: "does the response not equal y", "does the response not equal n". As the response cannot be "y" and "n" at the same time, at least one of those tests will always be true, and by using "or" your while test will always evaluate to true.