C#: How to convert long to ulong

c# long-integer ulong

31,019

Solution 1

A simple cast is all you need. Since it's possible to lose precision doing this, the conversion is explicit.

long x = 10;
ulong y = (ulong)x;

Solution 2

Try:

Convert.ToUInt32()

Solution 3

Given this function:

string test(long vLong)
{
    ulong vULong = (ulong)vLong;
    return string.Format("long hex: {0:X}, ulong hex: {1:X}", vLong, vULong);
}

And this usage:

    string t1 = test(Int64.MinValue);
    string t2 = test(Int64.MinValue + 1L);
    string t3 = test(-1L);
    string t4 = test(-2L);

This will be the result:

    t1 == "long hex: 8000000000000000, ulong hex: 8000000000000000"
    t2 == "long hex: 8000000000000001, ulong hex: 8000000000000001"
    t3 == "long hex: FFFFFFFFFFFFFFFF, ulong hex: FFFFFFFFFFFFFFFF"
    t4 == "long hex: FFFFFFFFFFFFFFFE, ulong hex: FFFFFFFFFFFFFFFE"

As you can see the bits are preserved completely, even for negative values.

Solution 4

To convert a long to a ulong, simply cast it:

long a;
ulong b = (ulong)a;

C# will NOT throw an exception if it is a negative number.

Solution 5

Int32 i = 17;
UInt32 j = (UInt32)i;

EDIT: question is unclear whether you have a long or an int?

View more solutions

31,019

Author by

P. Duw

Updated on July 09, 2022

Comments

P. Duw almost 2 years

If i try with BitConverter,it requires a byte array and i don't have that.I have a Int32 and i want to convert it to UInt32.

In C++ there was no problem with that.
Matthew Olenik about 15 years

I think John is referring to "old" longs in C or C++ that were 32 bits wide.
Tracker1 about 15 years

I don't beleive that this throws an exception with a negative value, but will not be what you expect... don't have .net on here (laptop), or would test it.
Matthew Olenik about 15 years

I meant that he referred to it out of habit.
Josh Stodola almost 14 years

Isn't this possible to overflow with big negatives? You can use unchecked to truncate instead: msdn.microsoft.com/en-us/library/a569z7k8(VS.71).aspx
DuneCat about 11 years

It won't, but the first bit will be interpreted as the most significant bit instead of the sign bit.
KFL about 11 years

It won't throw. You should consider revise your answer otherwise it could be misleading.
Patrick Hofman over 8 years

@KFL indeed. Updated.
adrianm over 8 years

If it throws or not is a compiler settings (Build/Advanced/Check for arithmetic overflow/underflow). To be safe you should always wrap it like ulong b = unchecked((ulong)a)