Change the amount of times code checks number-CodePudding

            Console.Write("Enter -");
            string input = Convert.ToString(Console.ReadLine());
            string ascii = input;
            byte[] ASCIIValues = Encoding.ASCII.GetBytes(ascii);
            for (int i = 0; i < input.Length; i  )
            {
                if (ASCIIValues[i] >= 48 && ASCIIValues[i] <= 57)
                {
                    Console.WriteLine("Is number");
                }
                else
                {
                    Console.WriteLine("Is not number");
                }
            }

I have made a code where it checks if you have entered number or not. It works fine while using only numbers from 1 to 9 . When I enter number with more digits the code checks each number. For example I enter 100 , and the code shows 3 lines "Is number." How could I change it , to only showing 1 line of "Is number."

CodePudding user response：

You are reading each char in the whole string and printing the result for each char... To follow your approach you should be checking the whole string first and print a positive result only if all char check was verified as a number.

Try something like this:

// ... your previous code
bool result = true;
for (int i = 0; i < input.Length; i  )
    if (ASCIIValues[i] >= 48 && ASCIIValues[i] <= 57)
        continue;
    else
    {
        result = false;
        break;
    }

if (result == true)
    Console.WriteLine("Is number");
else
    Console.WriteLine("Is not number");

Here I'm initializing a bool variable result with true value. If the code runs until the end of the loop with no break call, it would be considered a number. Otherwise, it would be false

Note: the char.IsNumber(char inputChar) function is a System's library function that does something like what you did with ASCII code checks. Using it, your code should look like this:

public static bool IsNumeric(string input)
{
    if(input.Length == 0)
        return false;
    
    for(int i = 0; i <input.Length; i  )
        if(!char.IsNumber(input[i]))
            return false;
           
    return true;
}

CodePudding user response：

Thats very complicated code for such a simple task

        Console.Write("Enter -");
        string input = Console.ReadLine();
        if(input.All(c=>Char.IsDigit(c)))
             Console.WriteLine("Is number");
        else
             Console.WriteLine("Is not a number");

or you could do this (since the next thing I expect you to do is convert that input to a number)

        Console.Write("Enter -");
        string input = Console.ReadLine();
        int num;
        if (Int32.TryParse(input, out num))
            Console.WriteLine("is a number");
        else
            Console.WriteLine("is not a number");

TryParse tries to convert the string to a number and reports success or failure