How could I convert data from string to long in c#

Question

How could i convert data from string to long in C#?

I have data

String strValue[i] =\"1100.25\";

now i want it in

long         


        

Answer 1

You can create your own conversion function:

    static long ToLong(string lNumber)
    {
        if (string.IsNullOrEmpty(lNumber))
            throw new Exception("Not a number!");
        char[] chars = lNumber.ToCharArray();
        long result = 0;
        bool isNegative = lNumber[0] == '-';
        if (isNegative && lNumber.Length == 1)
            throw new Exception("- Is not a number!");

        for (int i = (isNegative ? 1:0); i < lNumber.Length; i++)
        {
            if (!Char.IsDigit(chars[i]))
            {
                if (chars[i] == '.' && i < lNumber.Length - 1 && Char.IsDigit(chars[i+1]))
                {
                    var firstDigit = chars[i + 1] - 48;
                    return (isNegative ? -1L:1L) * (result + ((firstDigit < 5) ? 0L : 1L));    
                }
                throw new InvalidCastException($" {lNumber} is not a valid number!");
            }
            result = result * 10 + ((long)chars[i] - 48L);
        }
        return (isNegative ? -1L:1L) * result;
    }

It can be improved further:

• performance wise
• make the validation stricter in the sense that it currently doesn't care if characters after first decimal aren't digits
• specify rounding behavior as parameter for conversion function. it currently does rounding

Answer 2

You can also do using Int64.TryParse Method. It will return '0' if their is any string value but did not generate an error.

Int64 l1;

Int64.TryParse(strValue, out l1);

Answer 3

You won't be able to convert it directly to long because of the decimal point i think you should convert it into decimal and then convert it into long something like this:

String strValue[i] = "1100.25";
long l1 = Convert.ToInt64(Convert.ToDecimal(strValue));

hope this helps!

Answer 4

This answer no longer works, and I cannot come up with anything better then the other answers (see below) listed here. Please review and up-vote them.

Convert.ToInt64("1100.25")

Method signature from MSDN:

public static long ToInt64(
    string value
)

Answer 5

long l1 = Convert.ToInt64(strValue);

That should do it.

Answer 6

If you want to get the integer part of that number you must first convert it to a floating number then cast to long.

long l1 = (long)Convert.ToDouble("1100.25");

You can use Math class to round up the number as you like, or just truncate...

• Math.Round
• Math.Ceil