How to Validate Console Input as Integers

How do I validate a user input with int.TryParse to ensure the user entered an integer but also ensure the number was between 1 and 4

Ignoring your slight syntax error with the parentheses, let's go over your condition

while((!int.TryParse(Console.ReadLine(), out userInput))&& (userInput > 0 && userInput < 5)

"While not a successful parse and input is greater than 0 and input is less than 5, ask for input"

Does it sound right?

If the user input is not parsed, then the parse result is actually 0. This means as soon as the user enters garbage, the loop quits (because the !TryParse is true so C# moves on to the next condition which is 0, 0 is not greater than 0 so the whole && is false) , which is the opposite of what it used to do (keep asking upon garbage). Further more, if they don't enter garbage and do provide a value that you ask for, like 3, because 3 is greater than 0 and less than 5, they will be asked to enter another number.

How about this for a logic instead:

"While the parse failed OR the input was less than 1 OR the input was more than 4, ask again"

Remember that && and || stop early if they encounter a false/true respectively. If the parse passes, it gets flipped to a false by the !, so if you're using OR, C# moves on to checking the next, trying to find a true. If your parse didn't pass, the OR will stop at the first check because it found the true it was wanting

Now, have a go at implementing it..

C# Validate integer user input in class property

Try do something like that:

C#:

public Worker TryGetWorker()
{
    string input = Console.ReadLine();
    int index = -1;
    bool isInt = int.TryParse(input,out index);
    Worker worker = Data.GetWorkerByID(index);
    if (!isInt || worker == null)
    {
        Console.Write("Wrong input. Try again: ");
        return TryGetWorker();
    }
    else
        return worker;
}

validate several numeric user inputs C# Console

You need something like that, man. Collect all values to List and work with it :

        List<int> numbers = new List<int>();
        while (numbers.Count() < 10)
        {
            Console.Write("Enter the " + (numbers.Count() + 1) + "st number: ");
            int num;
            while (Int32.TryParse(Console.ReadLine(), out num) == false)
            {
                Console.WriteLine("Type a number please.");
            }
            numbers.Add(num);
        }

        int biggestNumber = numbers.Max();
        int smallestNumber = numbers.Min();
        Console.WriteLine("Your biggest number was: " + biggestNumber);
        Console.WriteLine("Your smallest number was: " + smallestNumber);

        int result = numbers.Sum()/numbers.Count();
        Console.WriteLine("The average of your numbers are: " + result);

        Console.ReadLine();

Validate console input in c++

For example:

bool is_number(const std::string& s)
{
    return !s.empty() && std::find_if(s.begin(), 
        s.end(), [](char c) { return !std::isdigit(c); }) == s.end();
}

foo() {
    char input[100];
    cin.getline(input, sizeof(input));
    stringstream stream(input);
    while (stream.rdbuf()->in_avail() != 0) {
        std::string n;
        stream >> n;
        if(is_number(n)) {
            numbers.push_back(std::stoi(n));
        }
        else {
            std::cout << "Not valid input. Provide number" << std::endl;
        }
    }
}

int main()
{
    foo();
    return 0;
}

How to validate user input to only allow numbers

If user inputs a letter or something that can't be converted to double your this piece of code double.TryParse will throw an exception and program will fail.

So you should use try-catch block here:

try
{
    userInput = double.Parse(Console.ReadLine());
    if (userInput == 999)
    {
        break;
    }
    else if (userInput < 0)
    {
        Console.WriteLine("Invalid input");
    } 
    else
    {
        scores[count++] = userInput;
    }
}
catch(Exception e)  // will take care of letters
{
    Console.WriteLine("You enter an Invalid input !"):
}

Console Application Input Validation for Int & Float Max Values C#

Working with ReadLine will be easier

bool validated = false;
int integerRequired;
Console.WriteLine("Type an integer number:");
while(validated == false)
{    
    string userInput = Console.ReadLine();
    validated  = int.TryParse (userInput, out integerRequired);
    if (!validated )
        Console.WriteLine("Not a valid integer, please retype a valid integer number");
}

float singleRequired;
validated = false;
Console.WriteLine("Type a floating point number:");
while(validated == false)
{    
    string userInput = Console.ReadLine();
    validated  = Single.TryParse (userInput, out singleRequired);
    if (!validated)
        Console.WriteLine("Not a valid float, please retype a valid float number");
}

In this example, you react to the user input only when he finishes to type and press enter. At this point you could evaluate the input using the version of TryParse appropriate for the input and choose to display or not an error message to the user.

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