---
name: "Nativeint"
section: "3o"
platform: "linux"
package: "ocaml"
version: "5.5.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Nativeint"
---

# Nativeint(3o)

Processor-native integers.

## NAME

Nativeint - Processor-native integers.

## Module

Module   Nativeint

## Documentation

Module **Nativeint**\
  :  **sig end**

Processor-native integers.

This module provides operations on the type  **nativeint** of signed 32-bit integers (on 32-bit platforms) or signed 64-bit integers (on 64-bit platforms). This integer type has exactly the same width as that of a pointer type in the C compiler.  All arithmetic operations over **nativeint** are taken modulo 2^32 or 2^64 depending on the word size of the architecture.

Performance notice: values of type  **nativeint** occupy more memory space than values of type  **int** , and arithmetic operations on **nativeint** are generally slower than those on  **int** .  Use  **nativeint** only when the application requires the extra bit of precision over the  **int** type.

Literals for native integers are suffixed by n:

```
     let zero: nativeint = 0n
     let one: nativeint = 1n
     let m_one: nativeint = -1n

```

*val zero* :  **nativeint**

The native integer 0.

*val one* :  **nativeint**

The native integer 1.

*val minus\_one* :  **nativeint**

The native integer -1.

*val neg* :  **nativeint -\> nativeint**

Unary negation.

*val add* :  **nativeint -\> nativeint -\> nativeint**

Addition.

*val sub* :  **nativeint -\> nativeint -\> nativeint**

Subtraction.

*val mul* :  **nativeint -\> nativeint -\> nativeint**

Multiplication.

*val div* :  **nativeint -\> nativeint -\> nativeint**

Integer division. This division rounds the real quotient of its arguments towards zero, as specified for  **(/)** .

**Raises Division\_by\_zero** if the second argument is zero.

*val unsigned\_div* :  **nativeint -\> nativeint -\> nativeint**

Same as  **Nativeint.div** , except that arguments and result are interpreted as     unsigned native integers.

**Since** 4.08

*val rem* :  **nativeint -\> nativeint -\> nativeint**

Integer remainder.  If  **y** is not zero, the result of  **Nativeint.rem x y** satisfies the following properties: **Nativeint.zero \<= Nativeint.rem x y \< Nativeint.abs y** and **x = Nativeint.add (Nativeint.mul (Nativeint.div x y) y)**\
                       **(Nativeint.rem x y)** . If  **y = 0** ,  **Nativeint.rem x y** raises  **Division\_by\_zero** .

*val unsigned\_rem* :  **nativeint -\> nativeint -\> nativeint**

Same as  **Nativeint.rem** , except that arguments and result are interpreted as     unsigned native integers.

**Since** 4.08

*val fdiv* :  **nativeint -\> nativeint -\> nativeint**

Floor division. **fdiv x y** is the real quotient  **x / y** rounded down to an integer. We have  **fdiv x y \<= div x y \<= cdiv x y** and  **cdiv x y - fdiv x y \<= 1** .

**Since** 5.5

**Raises Division\_by\_zero** if the second argument is 0.

*val cdiv* :  **nativeint -\> nativeint -\> nativeint**

Ceil division. **cdiv x y** is the real quotient  **x / y** rounded up to an integer. We have  **fdiv x y \<= div x y \<= cdiv x y** and  **cdiv x y - fdiv x y \<= 1** .

**Since** 5.5

**Raises Division\_by\_zero** if the second argument is 0.

*val ediv* :  **nativeint -\> nativeint -\> nativeint**

Euclidean division. **ediv x y** is the real quotient  **x / y** rounded down to an integer if  **y \> 0** and rounded up to an integer if  **y \< 0** . The remainder  **erem x y = x - ediv x y \* y** is always non-negative. Moreover,  **ediv x (-y)** =  **- ediv x y** .

**Since** 5.5

**Raises Division\_by\_zero** if the second argument is 0.

*val erem* :  **nativeint -\> nativeint -\> nativeint**

Euclidean remainder.  If  **y** is not zero, we have **x = ediv x y \* y + erem x y** and  **0 \<= erem x y \<= abs y - 1** . The result of  **erem x y** is always non-negative, unlike the result of  **rem x y** , which has the sign of  **x** .

**Since** 5.5

**Raises Division\_by\_zero** if the second argument is 0.

*val succ* :  **nativeint -\> nativeint**

Successor. **Nativeint.succ x** is  **Nativeint.add x Nativeint.one** .

*val pred* :  **nativeint -\> nativeint**

Predecessor. **Nativeint.pred x** is  **Nativeint.sub x Nativeint.one** .

*val abs* :  **nativeint -\> nativeint**

**abs x** is the absolute value of  **x** . On  **min\_int** this is  **min\_int** itself and thus remains negative.

*val size* :  **int**

The size in bits of a native integer.  This is equal to  **32** on a 32-bit platform and to  **64** on a 64-bit platform.

*val max\_int* :  **nativeint**

The greatest representable native integer, either 2^31 - 1 on a 32-bit platform, or 2^63 - 1 on a 64-bit platform.

*val min\_int* :  **nativeint**

The smallest representable native integer, either -2^31 on a 32-bit platform, or -2^63 on a 64-bit platform.

*val logand* :  **nativeint -\> nativeint -\> nativeint**

Bitwise logical and.

*val logor* :  **nativeint -\> nativeint -\> nativeint**

Bitwise logical or.

*val logxor* :  **nativeint -\> nativeint -\> nativeint**

Bitwise logical exclusive or.

*val lognot* :  **nativeint -\> nativeint**

Bitwise logical negation.

*val shift\_left* :  **nativeint -\> int -\> nativeint**

**Nativeint.shift\_left x y** shifts  **x** to the left by  **y** bits. The result is unspecified if  **y \< 0** or  **y \>= bitsize** , where  **bitsize** is  **32** on a 32-bit platform and **64** on a 64-bit platform.

*val shift\_right* :  **nativeint -\> int -\> nativeint**

**Nativeint.shift\_right x y** shifts  **x** to the right by  **y** bits. This is an arithmetic shift: the sign bit of  **x** is replicated and inserted in the vacated bits. The result is unspecified if  **y \< 0** or  **y \>= bitsize** .

*val shift\_right\_logical* :  **nativeint -\> int -\> nativeint**

**Nativeint.shift\_right\_logical x y** shifts  **x** to the right by  **y** bits. This is a logical shift: zeroes are inserted in the vacated bits regardless of the sign of  **x** . The result is unspecified if  **y \< 0** or  **y \>= bitsize** .

*val of\_int* :  **int -\> nativeint**

Convert the given integer (type  **int** ) to a native integer (type  **nativeint** ).

*val to\_int* :  **nativeint -\> int**

Convert the given native integer (type  **nativeint** ) to an integer (type  **int** ).  The high-order bit is lost during the conversion.

*val unsigned\_to\_int* :  **nativeint -\> int option**

Same as  **Nativeint.to\_int** , but interprets the argument as an unsigned integer. Returns  **None** if the unsigned value of the argument cannot fit into an **int** .

**Since** 4.08

*val of\_float* :  **float -\> nativeint**

Convert the given floating-point number to a native integer, discarding the fractional part (truncate towards 0). If the truncated floating-point number is outside the range \[ **Nativeint.min\_int** ,  **Nativeint.max\_int** \], no exception is raised, and an unspecified, platform-dependent integer is returned.

*val to\_float* :  **nativeint -\> float**

Convert the given native integer to a floating-point number.

*val of\_int32* :  **int32 -\> nativeint**

Convert the given 32-bit integer (type  **int32** ) to a native integer.

*val to\_int32* :  **nativeint -\> int32**

Convert the given native integer to a 32-bit integer (type  **int32** ).  On 64-bit platforms, the 64-bit native integer is taken modulo 2^32, i.e. the top 32 bits are lost.  On 32-bit platforms, the conversion is exact.

*val of\_string* :  **string -\> nativeint**

Convert the given string to a native integer. The string is read in decimal (by default, or if the string begins with  **0u** ) or in hexadecimal, octal or binary if the string begins with  **0x** ,  **0o** or  **0b** respectively.

The  **0u** prefix reads the input as an unsigned integer in the range **\[0, 2\*Nativeint.max\_int+1\]** .  If the input exceeds  **Nativeint.max\_int** it is converted to the signed integer **Int64.min\_int + input - Nativeint.max\_int - 1** .

**Raises Failure** if the given string is not a valid representation of an integer, or if the integer represented exceeds the range of integers representable in type  **nativeint** .

*val of\_string\_opt* :  **string -\> nativeint option**

Same as  **of\_string** , but return  **None** instead of raising.

**Since** 4.05

*val to\_string* :  **nativeint -\> string**

Return the string representation of its argument, in decimal.

*type t* =  **nativeint**

An alias for the type of native integers.

*val compare* :  **t -\> t -\> int**

The comparison function for native integers, with the same specification as **compare** .  Along with the type  **t** , this function  **compare** allows the module  **Nativeint** to be passed as argument to the functors **Set.Make** and  **Map.Make** .

*val unsigned\_compare* :  **t -\> t -\> int**

Same as  **Nativeint.compare** , except that arguments are interpreted as unsigned native integers.

**Since** 4.08

*val equal* :  **t -\> t -\> bool**

The equal function for native ints.

**Since** 4.03

*val min* :  **t -\> t -\> t**

Return the smaller of the two arguments.

**Since** 4.13

*val max* :  **t -\> t -\> t**

Return the greater of the two arguments.

**Since** 4.13

*val popcount* :  **t -\> int**

Population count, also known as Hamming weight. **popcount n** is the number of 1 bits in the binary representation of  **n** . Negative  **n** are represented in two's complement.

**Since** 5.5

*val unsigned\_bitsize* :  **t -\> int**

**unsigned\_bitsize n** is the minimal number of bits needed to represent **n** as an unsigned binary number.  It is the smallest integer  **i** between 0 and  **size** inclusive such that  **0 \<= n \< 2{^i}** (unsigned).

**Since** 5.5

*val signed\_bitsize* :  **t -\> int**

**signed\_bitsize n** is the minimal number of bits needed to represent **n** as a signed, two's complement binary number. It is the smallest integer  **i** between 1 and  **size** inclusive such that **-2{^i-1} \<= n \< 2{^i-1}** (signed).

**Since** 5.5

*val leading\_zeros* :  **t -\> int**

**leading\_zeros n** is the number of leading (most significant) 0 bits in the binary representation of  **n** . It is an integer between 0 and 64 inclusive. If  **n** is negative,  **leading\_zeros n = 0** since the most significant bit of  **n** is 1.   **leading\_zeros n = size** if and only if  **n = zero** . Note that  **leading\_zeros n + unsigned\_bitsize n = size** .

**Since** 5.5

*val leading\_sign\_bits* :  **t -\> int**

**leading\_sign\_bits n** is the number of leading (most significant) sign bits in the binary representation of  **n** , excluding the sign bit itself. It is an integer between 0 and 63 inclusive. For positive  **n** , it is the number of leading zero bits minus one. For negative  **n** , it is the number of leading one bits minus one. Note that  **leading\_sign\_bits n + signed\_bitsize n = size** .

**Since** 5.5

*val trailing\_zeros* :  **t -\> int**

**trailing\_zeros n** is the number of trailing (least significant) 0 bits in the binary representation of  **n** . It is an integer between 0 and  **size** inclusive. It is the largest integer  **i \<= size** such that  **2{^i}** divides  **n** evenly. For example,  **trailing\_zeros n = 0** if and only if  **n** is odd, and  **trailing\_zeros n = size** if and only if  **n = zero** .

**Since** 5.5

*val seeded\_hash* :  **int -\> t -\> int**

A seeded hash function for native ints, with the same output value as **Hashtbl.seeded\_hash** . This function allows this module to be passed as argument to the functor  **Hashtbl.MakeSeeded** .

**Since** 5.1

*val hash* :  **t -\> int**

An unseeded hash function for native ints, with the same output value as **Hashtbl.hash** . This function allows this module to be passed as argument to the functor  **Hashtbl.Make** .

**Since** 5.1