allocate(length: int, value: int = 0) -- 수신자
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- 최소 인자 수
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- 최대 인자 수
- 2
Declaration and parameters
링크사용 조건
기본 포함 · 미정
Import std.bytes in language mode 5.21.
The current compiler selects std/bytes.tpz for this language mode. Availability in other released editions and inclusion in each installed distribution are Pending.
수신자
매개변수 제약
ByteBuffer.allocate accepts a nonnegative int length and an int initial value from 0 through 255. The initial value defaults to zero.
The new buffer has exactly that many copies of the initial byte. Zero length is valid and still requires a valid initial byte.
A negative length produces TPZ4001 at runtime. An invalid initial byte or an allocation that cannot be satisfied produces TPZ5001 at runtime.
ByteBuffer.fromBytes converts an immutable Bytes value into a mutable ByteBuffer value containing the same bytes.
ByteBuffer.toBytes converts the current buffer contents into an immutable Bytes value.
ByteBuffer.length is a read-only byte count property. Buffer operations never change its length.
Assignment, argument passing, return, capture, and aggregate storage follow collection value semantics.
Supplied expressions evaluate once from left to right before allocation or conversion. These operations have no I/O effects.
관련 규칙 · Allocate buffers and convert byte values →결과
The declared result type is Byte.
효과
실패
Result and effects
링크Allocate a fixed buffer with a nonnegative byte count and a byte value from 0 through 255. The initial value defaults to zero.
Resolved contracts
링크Related entries
링크Allocate buffers and convert byte values
링크Allocate buffers and convert byte values
ByteBuffer.allocate accepts a nonnegative int length and an int initial value from 0 through 255. The initial value defaults to zero.
The new buffer has exactly that many copies of the initial byte. Zero length is valid and still requires a valid initial byte.
A negative length produces TPZ4001 at runtime. An invalid initial byte or an allocation that cannot be satisfied produces TPZ5001 at runtime.
ByteBuffer.fromBytes converts an immutable Bytes value into a mutable ByteBuffer value containing the same bytes.
ByteBuffer.toBytes converts the current buffer contents into an immutable Bytes value.
ByteBuffer.length is a read-only byte count property. Buffer operations never change its length.
Assignment, argument passing, return, capture, and aggregate storage follow collection value semantics.
Supplied expressions evaluate once from left to right before allocation or conversion. These operations have no I/O effects.
이유
A fixed length gives binary algorithms stable byte positions. Explicit conversion distinguishes mutable construction from immutable byte data.
Allocate zero-filled and initialized buffers
링크import std.bytes { ByteBuffer }import std.ioio.writeLine(ByteBuffer.allocate(0).toBytes().toHex())io.writeLine(ByteBuffer.allocate(3).toBytes().toHex())io.writeLine(ByteBuffer.allocate(2, 255).toBytes().toHex())
000000
ffff
기대 결과
기대 결과
실행을 마칩니다. 종료 코드 0.
000000ffff
Keep the original buffer and converted bytes unchanged
링크import std.bytes { ByteBuffer }import std.iolet source = "ab".encodeUtf8()let buffer = ByteBuffer.fromBytes(source)let independent = ByteBuffer.fromBytes(source)let before = buffer.toBytes()let mut alias = bufferalias.set(0, 99)io.writeLine(source.toHex())io.writeLine(before.toHex())io.writeLine(independent.toBytes().toHex())io.writeLine(buffer.toBytes().toHex())
6162
6162
6162
6162
기대 결과
기대 결과
실행을 마칩니다. 종료 코드 0.
6162616261626162
Reject a negative buffer length
링크import std.bytes { ByteBuffer }ByteBuffer.allocate(-1)
표준 출력 없음.기대 결과
Validate the initial byte of an empty buffer
링크import std.bytes { ByteBuffer }import std.ioByteBuffer.allocate(0, -1)io.writeLine("after")
표준 출력 없음.기대 결과
Validate the initial byte of an empty buffer
링크import std.bytes { ByteBuffer }import std.ioByteBuffer.allocate(0, 256)io.writeLine("after")
표준 출력 없음.