Question

I have a string variable which has a mixture of numbers and letters. I want to create a new string that only has int values of the previous string variable. So I found two ways to cast int to char. However, they do not work. Here’s what I’ve tried

string onlyNumberString = "";
foreach (char onlyNum in puzzleData)
{
    for (int i = 1; i < 10; i++)
    {
        if (onlyNum == (char)i)
        {
            onlyNumberString += onlyNum;
        }
    }
}

and

string onlyNumberString = "";
foreach (char onlyNum in puzzleData)
{
    for (int i = 1; i < 10; i++)
    {
        if (onlyNum == Convert.ToChar(i))
        {
            onlyNumberString += onlyNum;
        }
    }
}

Answer 1

Use Char.IsDigit instead, far simpler.

StringBuilder onlyNumber = new StringBuilder();
foreach (char onlyNum in puzzleData)
{
    if (Char.IsDigit(onlyNum))
    {
        onlyNumber.Append(onlyNum);
    }
}