【move】3.Integers

整數(shù) (Integers)

Move supports three unsigned integer types: u8, u64, and u128. Values of these types range from 0 to a maximum that depends on the size of the type.

Type Value Range
Unsigned 8-bit integer, u8 0 to 28 - 1
Unsigned 64-bit integer, u64 0 to 264 - 1
Unsigned 128-bit integer, u128 0 to 2128 - 1

Move 支持三種無符號整數(shù)類型:u8、u64u128。這些類型的值范圍從 0 到最大值,最大值的具體取值取決于整數(shù)類型。

類型 取值范圍
無符號 8位 整數(shù), u8 0 to 28 - 1
無符號 64位 整數(shù), u64 0 to 264 - 1
無符號 128位 整數(shù), u128 0 to 2128 - 1

字面值(Literal)

Literal values for these types are specified either as a sequence of digits (e.g.,112) or as hex literals, e.g., 0xFF. The type of the literal can optionally be added as a suffix, e.g., 112u8. If the type is not specified, the compiler will try to infer the type from the context where the literal is used. If the type cannot be inferred, it is assumed to be u64.

If a literal is too large for its specified (or inferred) size range, an error is reported.

(在Move中)這些類型的字面值指定為數(shù)字序列(例如:112)或十六進制文字(例如:0xFF), 可以選擇將字面值的類型定義為后綴, 例如 112u8。如果未指定類型,編譯器將嘗試從使用字面值的上下文推斷類型。如果無法推斷類型,則默認為 `u64。

如果字面值太大,超出其指定的(或推斷的)大小范圍,則會報錯。

例如:

// literals with explicit annotations;
let explicit_u8 = 1u8;
let explicit_u64 = 2u64;
let explicit_u128 = 3u128;

// literals with simple inference
let simple_u8: u8 = 1;
let simple_u64: u64 = 2;
let simple_u128: u128 = 3;

// literals with more complex inference
let complex_u8 = 1; // inferred: u8
// right hand argument to shift must be u8
let _unused = 10 << complex_u8;

let x: u8 = 0;
let complex_u8 = 2; // inferred: u8
// arguments to `+` must have the same type
let _unused = x + complex_u8;

let complex_u128 = 3; // inferred: u128
// inferred from function argument type
function_that_takes_u128(complex_u128);

// literals can be written in hex
let hex_u8: u8 = 0x1;
let hex_u64: u64 = 0xCAFE;
let hex_u128: u128 = 0xDEADBEEF;

運算集 (Operations)

算術運算 (Arithmetic)

Each of these types supports the same set of checked arithmetic operations. For all of these operations, both arguments (the left and right side operands) must be of the same type. If you need to operate over values of different types, you will need to first perform a cast. Similarly, if you expect the result of the operation to be too large for the integer type, perform a cast to a larger size before performing the operation.

每一種(無符號整數(shù))類型都支持相同算術運算集。對于所有這些運算,兩個參數(shù)(左側和右側操作數(shù))必須是同一類型。如果您需要對不同類型的值進行運算,則需要首先執(zhí)行強制轉換。同樣,如果您預計運算結果對于當下整數(shù)類型來說太大,請在執(zhí)行運算之前將之轉換為更大的整數(shù)類型。

All arithmetic operations abort instead of behaving in a way that mathematical integers would not (e.g., overflow, underflow, divide-by-zero).

Syntax Operation Aborts If
+ addition Result is too large for the integer type
- subtraction Result is less than zero
* multiplication Result is too large for the integer type
% modular division The divisor is 0
/ truncating division The divisor is 0

Bitwise

算術運算在遇到異常時將會中止,而不是以上溢、下溢、被零除等數(shù)學整數(shù)未定義的的方式輸出結果。

句法 操作 中止條件
+ 加法 結果對于整數(shù)類型來說太大了
- 減法 結果小于零
* 乘法 結果對于整數(shù)類型來說太大了
% 取余運算 除數(shù)為 0
/ 截斷除法 除數(shù)為 0

位運算 (Bitwise)

The integer types support the following bitwise operations that treat each number as a series of individual bits, either 0 or 1, instead of as numerical integer values.

Bitwise operations do not abort.

Syntax Operation Description
& bitwise and Performs a boolean and for each bit pairwise
` ` bitwise or Performs a boolean or for each bit pairwise
^ bitwise xor Performs a boolean exclusive or for each bit pairwise

整數(shù)類型支持下列位運算,即將每個數(shù)字視為一系列單獨的位:0 或 1,而不是整型數(shù)值。

位運算不會中止。

句法 操作 描述
& 按位 和 對每個位成對執(zhí)行布爾值和
` ` 按位或 對每個位成對執(zhí)行布爾值或
^ 按位 異與 對每個位成對執(zhí)行布爾異或

位移 (Bit shift)

Similar to the bitwise operations, each integer type supports bit shifts. But unlike the other operations, the righthand side operand (how many bits to shift by) must always be a u8 and need not match the left side operand (the number you are shifting).

Bit shifts can abort if the number of bits to shift by is greater than or equal to 8, 64, or 128 for u8, u64, and u128 respectively.

Syntax Operation Aborts if
<< shift left Number of bits to shift by is greater than the size of the integer type
>> shift right Number of bits to shift by is greater than the size of the integer type

與按位運算類似,每種整數(shù)類型都支持位移(bit shifts)。但與其他運算不同的是,右側操作數(shù)(要移位多少位)必須始終是 u8 并且不需要與左側操作數(shù)類型(您要移位的數(shù)字)匹配。

如果要移位的位數(shù)分別大于或等于 8、64, u128128u8, u64, 則移位可以中止。

句法 操作 中止條件
<< 左移 要移位的位數(shù)大于整數(shù)類型的大小
>> 右移 要移位的位數(shù)大于整數(shù)類型的大小

比較運算 (Comparisons)

Integer types are the only types in Move that can use the comparison operators. Both arguments need to be of the same type. If you need to compare integers of different types, you will need to cast one of them first.

Comparison operations do not abort.

Syntax Operation
< less than
> greater than
<= less than or equal to
>= greater than or equal to

整數(shù)類型是 Move 中唯一可以使用比較(Comparisons)運算符的類型。兩個參數(shù)必須是同一類型。如果您需要比較不同類型的整數(shù),則需要先轉換其中一個。

比較操作不會中止。

句法 操作
< 小于
> 大于
<= 小于等于
>= 大于等于

相等 (Equality)

Like all types with drop in Move, all integer types support the "equal" and "not equal" operations. Both arguments need to be of the same type. If you need to compare integers of different types, you will need to cast one of them first.

Equality operations do not abort.

Syntax Operation
== equal
!= not equal

For more details see the section on equality

與 Move 中的所有具有drop能力的類型一樣,所有整數(shù)類型都支持 "equal(等于)""not equal(不等于)運算。兩個參數(shù)必須是同一類型。如果您需要比較不同類型的整數(shù),則需要先轉換其中一個。

相等(Equality)運算不會中止。

句法 操作
== 等于
!= 不等于

更多細節(jié)可以參考相等章節(jié)。

轉換 (Casting)

Integer types of one size can be cast to integer types of another size. Integers are the only types in Move that support casting.

Casts do not truncate. Casting will abort if the result is too large for the specified type

Syntax Operation Aborts if
(e as T) Cast integer expression e into an integer type T e is too large to represent as a T

Here, the type of e must be u8, u64, or u128 and T must be u8, u64, or u128.

For example:

  • (x as u8)
  • (2u8 as u64)
  • (1 + 3 as u128)

一種大小的整數(shù)類型可以轉換為另一種大小的整數(shù)類型。整數(shù)是 Move 中唯一支持強制轉換的類型。

強制轉換不會截斷。如果結果對于指定類型來說太大,則轉換將中止。

Syntax 操作 中止條件
(e as T) 將整數(shù)表達式 e 轉換為整數(shù)類型 T e 太大而不能表示為 T

所有權 (Ownership)

As with the other scalar values built-in to the language, integer values are implicitly copyable, meaning they can be copied without an explicit instruction such as copy.

與語言內(nèi)置的其他標量值一樣,整數(shù)值是隱式可復制的,這意味著它們可以在沒有明確指令如copy的情況下復制。

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