C#: Count Number of Digits in a String Using Do While Loop-CodePudding

Hi I would appreciate if you could help me to fix this code. I am required to use Do While Loop. I am receiving "Outside Bound" error. I believe I need to substract or add 1 somewhere but can't figure out exactly where.

public static int Digit(string str)
        {
            if (str is null)
            {
                throw new ArgumentNullException(nameof(str));
            }

            int count = 0;
            int i = 0;
            do
            {
                if (char.IsDigit(str[i]))
                {
                    count  ;
                }

                i  ;
            }
            while (i < str.Length);

            return count;
        }

Thank you in advance.

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CodePudding user response：

you have to fix validation, you exception was when string was empty, but not null

if (string.IsNullOrEmpty(str))
        throw new ArgumentNullException(nameof(str));

CodePudding user response：

Since do .. while executes at least once, you have a special case for an empty string:

public static int Digit(string str)
{
    if (str is null)
        throw new ArgumentNullException(nameof(str));
    
    if (string.IsNullOrEmpty(str))
        return 0;

    int count = 0;
    int i = 0;

    do
    {
        if (char.IsDigit(str[i  ])) // Let's make it compact
            count  ;
    }
    while (i < str.Length);

    return count;
}