Simple validating c input event dating parties

However, this function is still subject to several constraints: if #, @, _, and ?are valid characters in the user input, this function won’t work, because those symbols have been given special meanings.

Although these flags live in ios_base, because ios is derived from ios_base and ios takes less typing than ios_base, they are generally accessed through ios (eg. ios also provides a number of member functions in order to conveniently access these states: Note that this program is expecting the user to enter an integer.

However, if the user enters non-numeric data, such as “Alex”, cin will be unable to extract anything to n Age, and the failbit will be set.

If our input was valid, gcount() should return 1 (the newline character that was discarded).

If it returns more than 1, the user entered something that wasn’t extracted properly, and we should ask them for new input.

If anything else is encountered, the input will be rejected.

When it comes to variable length inputs, the best way to validate strings (besides using a regular expression library) is to step through each character of the string and ensure it meets the validation criteria. Note that this code isn’t perfect: the user could say their name was “asf w jweo s di we ao” or some other bit of gibberish, or even worse, just a bunch of spaces.

Unlike a user’s name, which is variable-length and where the validation criteria are the same for every character, a phone number is a fixed length but the validation criteria differ depending on the position of the character.

Consequently, we are going to take a different approach to validating our phone number input.

Fortunately, the previous solution gets us half way there.

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