# Difference between '::UInt64' and '::Type(UInt64)'

**URL:** https://discourse.julialang.org/t/difference-between-uint64-and-type-uint64/107355
**Category:** General Usage
**Tags:** question
**Created:** [December 9, 2023, 11:55am UTC](https://discourse.julialang.org/t/difference-between-uint64-and-type-uint64/107355 "2023-12-09T11:55:38Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![jiang\_ming\_zhang](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jiang_ming_zhang/32/204063_2.png) [@jiang\_ming\_zhang](https://discourse.julialang.org/u/jiang_ming_zhang)
#### Post date: [December 9, 2023, 11:55am UTC](https://discourse.julialang.org/t/difference-between-uint64-and-type-uint64/107355/1 "2023-12-09T11:55:38Z")

</div>

I saw functions defined as

```julia
function check_bitstring_typeparams(::Val{B}, ::Val{1}, ::Type{UInt64}) where {B}
    if B > 64
        error("$B bits do not fit into a 64-bit chunk")
    end
end

```

What is the difference between ‘::UInt64’ and ‘::Type(UInt64)’?

For ‘::UInt64’, I know I need to input an unsigned integer with 64 bits, but what should I input for ‘::Type(UInt64)’?

---

<div class="post-metadata">

### Author: ![fatteneder](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fatteneder/32/33991_2.png) [@fatteneder](https://discourse.julialang.org/u/fatteneder)
#### Post date: [December 9, 2023, 12:02pm UTC](https://discourse.julialang.org/t/difference-between-uint64-and-type-uint64/107355/2 "2023-12-09T12:02:44Z")

</div>

> [@jiang\_ming\_zhang](#):
>
> For ‘::UInt64’, I know I need to input an unsigned integer with 64 bits, but what should I input for ‘::Type(UInt64)’?

You put `UInt64`. Example:

```julia-repl
julia> f(x::UInt64) = 1
f (generic function with 1 methods)

julia> f(x::Type{UInt64}) = 2
f (generic function with 2 methods)

julia> f(UInt64(5))
1

julia> f(UInt64)
2

```