What is fastest: (int), Convert.ToInt32(x) or Int32.Parse(x)?

Question

Which of the following code is fastest/best practice for converting some object x?

int myInt = (int)x;

or

int myInt = Convert.T         


        

Answer 1

Extending the test of Eric Cosky by alternatives from Sam Allen, i found that if you know that your string is a valid integer, then parsing it by yourself is much faster.

I extended the test by the following cases:

    timer1000.Measure("IntParseFast", 10, delegate
    {
        result = Misc.IntParseFast(strInput);
    });

    timer1000.Measure("IntParseUnsafe", 10, delegate
    {
        result = Misc.IntParseUnsafe(strInput);
    });

With the following implementations:

public static int IntParseFast(string value)
{
    int result = 0;
    int length = value.Length;
    for (int i = 0; i < length; i++)
    {
        result = 10 * result + (value[i] - 48);
    }
    return result;
}

public unsafe static int IntParseUnsafe(string value)
{
    int result = 0;
    fixed (char* v = value)
    {
        char* str = v;
        while (*str != '\0')
        {
            result = 10 * result + (*str - 48);
            str++;
        }
    }
    return result;
}

I get the following results:

IntCaint.Parse                5,495
IntCaConvert.ToInt32          5,653
IntCaIntParseFast             1,154
IntCaIntParseUnsafe           1,245