# Numeric IntPtr

Note

This article is a feature specification. The specification serves as the design document for the feature. It includes proposed specification changes, along with information needed during the design and development of the feature. These articles are published until the proposed spec changes are finalized and incorporated in the current ECMA specification.

There may be some discrepancies between the feature specification and the completed implementation. Those differences are captured in the pertinent language design meeting (LDM) notes.

You can learn more about the process for adopting feature speclets into the C# language standard in the article on the specifications.

## Summary

This is a revision on the initial native integers feature (spec), where the `nint`

/`nuint`

types were distinct from the underlying types `System.IntPtr`

/`System.UIntPtr`

.
In short, we now treat `nint`

/`nuint`

as simple types aliasing `System.IntPtr`

/`System.UIntPtr`

, like we do for `int`

in relation to `System.Int32`

. The `System.Runtime.CompilerServices.RuntimeFeature.NumericIntPtr`

runtime feature flag triggers this new behavior.

## Design

### 8.3.5 Simple types

C# provides a set of predefined `struct`

types called the simple types. The simple types are identified through keywords, but these keywords are simply aliases for predefined `struct`

types in the `System`

namespace, as described in the table below.

Keyword |
Aliased type |
---|---|

`sbyte` |
`System.SByte` |

`byte` |
`System.Byte` |

`short` |
`System.Int16` |

`ushort` |
`System.UInt16` |

`int` |
`System.Int32` |

`uint` |
`System.UInt32` |

`nint` |
`System.IntPtr` |

`nuint` |
`System.UIntPtr` |

`long` |
`System.Int64` |

`ulong` |
`System.UInt64` |

`char` |
`System.Char` |

`float` |
`System.Single` |

`double` |
`System.Double` |

`bool` |
`System.Boolean` |

`decimal` |
`System.Decimal` |

[...]

### 8.3.6 Integral types

C# supports **eleven** integral types: `sbyte`

, `byte`

, `short`

, `ushort`

, `int`

, `uint`

, ** nint, nuint**,

`long`

, `ulong`

, and `char`

. [...]## 8.8 Unmanaged types

In other words, an *unmanaged_type* is one of the following:

`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`char`

,`float`

,`double`

,`decimal`

, or`bool`

.- Any
*enum_type*. - Any user-defined
*struct_type*that is not a constructed type and contains fields of*unmanaged_type*s only. - In unsafe code, any
*pointer_type*.

### 10.2.3 Implicit numeric conversions

The implicit numeric conversions are:

- From
`sbyte`

to`short`

,`int`

,,`nint`

`long`

,`float`

,`double`

, or`decimal`

. - From
`byte`

to`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`float`

,`double`

, or`decimal`

. - From
`short`

to`int`

,,`nint`

`long`

,`float`

,`double`

, or`decimal`

. - From
`ushort`

to`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`float`

,`double`

, or`decimal`

. - From
`int`

to,`nint`

`long`

,`float`

,`double`

, or`decimal`

. - From
`uint`

to,`nuint`

`long`

,`ulong`

,`float`

,`double`

, or`decimal`

. **From**`nint`

to`long`

,`float`

,`double`

, or`decimal`

.**From**`nuint`

to`ulong`

,`float`

,`double`

, or`decimal`

.- From
`long`

to`float`

,`double`

, or`decimal`

. - From
`ulong`

to`float`

,`double`

, or`decimal`

. - From
`char`

to`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`float`

,`double`

, or`decimal`

. - From
`float`

to`double`

.

[...]

### 10.2.11 Implicit constant expression conversions

An implicit constant expression conversion permits the following conversions:

- A
*constant_expression*of type`int`

can be converted to type`sbyte`

,`byte`

,`short`

,`ushort`

,`uint`

,, or`nint`

,`nuint`

`ulong`

, provided the value of the*constant_expression*is within the range of the destination type. [...]

### 10.3.2 Explicit numeric conversions

The explicit numeric conversions are the conversions from a *numeric_type* to another *numeric_type* for which an implicit numeric conversion does not already exist:

- From
`sbyte`

to`byte`

,`ushort`

,`uint`

,,`nuint`

`ulong`

, or`char`

. - From
`byte`

to`sbyte`

or`char`

. - From
`short`

to`sbyte`

,`byte`

,`ushort`

,`uint`

,,`nuint`

`ulong`

, or`char`

. - From
`ushort`

to`sbyte`

,`byte`

,`short`

, or`char`

. - From
`int`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`uint`

,,`nuint`

`ulong`

, or`char`

. - From
`uint`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,, or`nint`

`char`

. - From
`long`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`ulong`

, or`char`

. **From**`nint`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,`nuint`

,`ulong`

, or`char`

.**From**`nuint`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,`nint`

,`long`

, or`char`

.- From
`ulong`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

, or`char`

. - From
`char`

to`sbyte`

,`byte`

, or`short`

. - From
`float`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`char`

, or`decimal`

. - From
`double`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`char`

,`float`

, or`decimal`

. - From
`decimal`

to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`char`

,`float`

, or`double`

.

[...]

### 10.3.3 Explicit enumeration conversions

The explicit enumeration conversions are:

- From
`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`char`

,`float`

,`double`

, or`decimal`

to any*enum_type*. - From any
*enum_type*to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

,`char`

,`float`

,`double`

, or`decimal`

. - From any
*enum_type*to any other*enum_type*.

#### 11.6.4.6 Better conversion target

Given two types `T₁`

and `T₂`

, `T₁`

is a * better conversion target* than

`T₂`

if one of the following holds:- An implicit conversion from
`T₁`

to`T₂`

exists and no implicit conversion from`T₂`

to`T₁`

exists `T₁`

is`Task<S₁>`

,`T₂`

is`Task<S₂>`

, and`S₁`

is a better conversion target than`S₂`

`T₁`

is`S₁`

or`S₁?`

where`S₁`

is a signed integral type, and`T₂`

is`S₂`

or`S₂?`

where`S₂`

is an unsigned integral type. Specifically: [...]

### 11.7.10 Element access

[...] The number of expressions in the *argument_list* shall be the same as the rank of the *array_type*, and each expression shall be of type `int`

, `uint`

, ** nint, nuint**,

`long`

, or `ulong,`

or shall be implicitly convertible to one or more of these types.#### 11.7.10.2 Array access

[...] The number of expressions in the *argument_list* shall be the same as the rank of the *array_type*, and each expression shall be of type `int`

, `uint`

, ** nint, nuint**,

`long`

, or `ulong,`

or shall be implicitly convertible to one or more of these types.[...] The run-time processing of an array access of the form `P[A]`

, where `P`

is a *primary_no_array_creation_expression* of an *array_type* and `A`

is an *argument_list*, consists of the following steps:
[...]

- The index expressions of the
*argument_list*are evaluated in order, from left to right. Following evaluation of each index expression, an implicit conversion to one of the following types is performed:`int`

,`uint`

,,`nint`

,`nuint`

`long`

,`ulong`

. The first type in this list for which an implicit conversion exists is chosen. [...]

### 11.7.14 Postfix increment and decrement operators

Unary operator overload resolution is applied to select a specific operator implementation. Predefined `++`

and `--`

operators exist for the following types: `sbyte`

, `byte`

, `short`

, `ushort`

, `int`

, `uint`

, `nint`

, `nuint`

,`long`

, `ulong`

, `char`

, `float`

, `double`

, `decimal`

, and any enum type.

### 11.8.2 Unary plus operator

The predefined unary plus operators are:

```
...
nint operator +(nint x);
nuint operator +(nuint x);
```

### 11.8.3 Unary minus operator

The predefined unary minus operators are:

Integer negation:

`... nint operator –(nint x);`

### 11.7.14 Postfix increment and decrement operators

Predefined `++`

and `--`

operators exist for the following types: `sbyte`

, `byte`

, `short`

, `ushort`

, `int`

, `uint`

, ** nint, nuint**,

`long`

, `ulong`

, `char`

, `float`

, `double`

, `decimal`

, and any enum type.### 11.7.19 Default value expressions

In addition, a *default_value_expression* is a constant expression if the type is one of the following value types: `sbyte`

, `byte`

, `short`

, `ushort`

, `int`

, `uint`

, ** nint, nuint**,

`long`

, `ulong`

, `char`

, `float`

, `double`

, `decimal`

, `bool,`

or any enumeration type.### 11.8.5 Bitwise complement operator

The predefined bitwise complement operators are:

```
...
nint operator ~(nint x);
nuint operator ~(nuint x);
```

### 11.8.6 Prefix increment and decrement operators

Predefined `++`

and `--`

operators exist for the following types: `sbyte`

, `byte`

, `short`

, `ushort`

, `int`

, `uint`

, ** nint, nuint**,

`long`

, `ulong`

, `char`

, `float`

, `double`

, `decimal`

, and any enum type.## 11.9 Arithmetic operators

### 11.9.2 Multiplication operator

The predefined multiplication operators are listed below. The operators all compute the product of `x`

and `y`

.

Integer multiplication:

`... nint operator *(nint x, nint y); nuint operator *(nuint x, nuint y);`

### 11.9.3 Division operator

The predefined division operators are listed below. The operators all compute the quotient of `x`

and `y`

.

Integer division:

`... nint operator /(nint x, nint y); nuint operator /(nuint x, nuint y);`

### 11.9.4 Remainder operator

The predefined remainder operators are listed below. The operators all compute the remainder of the division between `x`

and `y`

.

Integer remainder:

`... nint operator %(nint x, nint y); nuint operator %(nuint x, nuint y);`

### 11.9.5 Addition operator

Integer addition:

`... nint operator +(nint x, nint y); nuint operator +(nuint x, nuint y);`

### 11.9.6 Subtraction operator

Integer subtraction:

`... nint operator –(nint x, nint y); nuint operator –(nuint x, nuint y);`

## 11.10 Shift operators

The predefined shift operators are listed below.

Shift left:

`... nint operator <<(nint x, int count); nuint operator <<(nuint x, int count);`

Shift right:

`... nint operator >>(nint x, int count); nuint operator >>(nuint x, int count);`

The

`>>`

operator shifts`x`

right by a number of bits computed as described below.When

`x`

is of type`int`

,or`nint`

`long`

, the low-order bits of`x`

are discarded, the remaining bits are shifted right, and the high-order empty bit positions are set to zero if`x`

is non-negative and set to one if`x`

is negative.When

`x`

is of type`uint`

,or`nuint`

`ulong`

, the low-order bits of`x`

are discarded, the remaining bits are shifted right, and the high-order empty bit positions are set to zero.Unsigned shift right:

`... nint operator >>>(nint x, int count); nuint operator >>>(nuint x, int count);`

For the predefined operators, the number of bits to shift is computed as follows: [...]

- When the type of
`x`

is`nint`

or`nuint`

, the shift count is given by the low-order five bits of`count`

on a 32 bit platform, or the lower-order six bits of`count`

on a 64 bit platform.

## 11.11 Relational and type-testing operators

### 11.11.2 Integer comparison operators

The predefined integer comparison operators are:

```
...
bool operator ==(nint x, nint y);
bool operator ==(nuint x, nuint y);
bool operator !=(nint x, nint y);
bool operator !=(nuint x, nuint y);
bool operator <(nint x, nint y);
bool operator <(nuint x, nuint y);
bool operator >(nint x, nint y);
bool operator >(nuint x, nuint y);
bool operator <=(nint x, nint y);
bool operator <=(nuint x, nuint y);
bool operator >=(nint x, nint y);
bool operator >=(nuint x, nuint y);
```

## 11.12 Logical operators

### 11.12.2 Integer logical operators

The predefined integer logical operators are:

```
...
nint operator &(nint x, nint y);
nuint operator &(nuint x, nuint y);
nint operator |(nint x, nint y);
nuint operator |(nuint x, nuint y);
nint operator ^(nint x, nint y);
nuint operator ^(nuint x, nuint y);
```

## 11.20 Constant expressions

A constant expression may be either a value type or a reference type. If a constant expression is a value type, it must be one of the following types: `sbyte`

, `byte`

, `short`

, `ushort`

, `int`

, `uint`

, ** nint, nuint**,

`long`

, `ulong`

, `char`

, `float`

, `double`

, `decimal`

, `bool,`

or any enumeration type.[...]

An implicit constant expression conversion permits a constant expression of type `int`

to be converted to `sbyte`

, `byte`

, `short`

, `ushort`

, `uint`

, ** nint, nuint,** or

`ulong`

, provided the value of the constant expression is within the range of the destination type.## 16.4 Array element access

Array elements are accessed using *element_access* expressions of the form `A[I₁, I₂, ..., Iₓ]`

, where `A`

is an expression of an array type and each `Iₑ`

is an expression of type `int`

, `uint`

, `nint`

, `nuint`

,`long`

, `ulong`

, or can be implicitly converted to one or more of these types. The result of an array element access is a variable, namely the array element selected by the indices.

## 22.5 Pointer conversions

### 22.5.1 General

[...]

Additionally, in an unsafe context, the set of available explicit conversions is extended to include the following explicit pointer conversions:

- From any
*pointer_type*to any other*pointer_type*. - From
`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,`nint`

,`nuint`

,`long`

, or`ulong`

to any*pointer_type*. - From any
*pointer_type*to`sbyte`

,`byte`

,`short`

,`ushort`

,`int`

,`uint`

,`nint`

,`nuint`

,`long`

, or`ulong`

.

### 22.6.4 Pointer element access

[...]
In a pointer element access of the form `P[E]`

, `P`

shall be an expression of a pointer type other than `void*`

, and `E`

shall be an expression that can be implicitly converted to `int`

, `uint`

, `nint`

, `nuint`

,`long`

, or `ulong`

.

### 22.6.7 Pointer arithmetic

In an unsafe context, the `+`

operator and `–`

operator can be applied to values of all pointer types except `void*`

. Thus, for every pointer type `T*`

, the following operators are implicitly defined:

```
[...]
T* operator +(T* x, nint y);
T* operator +(T* x, nuint y);
T* operator +(nint x, T* y);
T* operator +(nuint x, T* y);
T* operator -(T* x, nint y);
T* operator -(T* x, nuint y);
```

Given an expression `P`

of a pointer type `T*`

and an expression `N`

of type `int`

, `uint`

, `nint`

, `nuint`

,`long`

, or `ulong`

, the expressions `P + N`

and `N + P`

compute the pointer value of type `T*`

that results from adding `N * sizeof(T)`

to the address given by `P`

. Likewise, the expression `P – N`

computes the pointer value of type `T*`

that results from subtracting `N * sizeof(T)`

from the address given by `P`

.

## Various considerations

### Breaking changes

One of the main impacts of this design is that `System.IntPtr`

and `System.UIntPtr`

gain some built-in operators (conversions, unary and binary).

Those include `checked`

operators, which means that the following operators on those types will now throw when overflowing:

`IntPtr + int`

`IntPtr - int`

`IntPtr -> int`

`long -> IntPtr`

`void* -> IntPtr`

### Metadata encoding

This design means that `nint`

and `nuint`

can simply be emitted as `System.IntPtr`

and `System.UIntPtr`

, without the use of `System.Runtime.CompilerServices.NativeIntegerAttribute`

.

Similarly, when loading metadata `NativeIntegerAttribute`

can be ignored.

C# feature specifications

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