Decimal.toInt

Declaration and parameters

사용 조건

기본 포함 · 미정

Import std.decimal in language mode 5.21.

The current compiler selects std/decimal.tpz for this language mode. Availability in other released editions and inclusion in each installed distribution are Pending.

수신자

Decimal

매개변수 제약

추가 계약은 미정입니다.

int.toDecimal converts every int value exactly and produces scale zero. Both signed 64 bit endpoints are representable. The conversion does not pass through float.

Decimal.toInt returns Some containing the same integer when the Decimal is integral and fits the integer conversion bounds.

A nonintegral Decimal or an integer outside the int range returns None(). Conversion does not round, truncate, wrap, saturate, or raise an arithmetic overflow fault. The original Decimal remains unchanged.

A value parsed from 1.000 is integral after normalization and converts to Some containing 1. A value parsed from 1.001 is nonintegral and returns None().

Existing int, float and BigInt values do not implicitly become Decimal values in arithmetic or comparisons. The module provides no direct float or BigInt conversion member.

For an exact BigInt conversion, format it with radix 10 and pass that text to Decimal.parse. To request an integral BigInt from a Decimal, pass its canonical text to BigInt.parse with radix 10. Fractional decimal text is rejected by that integer parser.

Converting through explicitly chosen text follows the corresponding text parser. Decimal.parse never recovers decimal digits that were lost in an earlier binary float calculation.

결과

추가 계약은 미정입니다.

The declared result type is Option<int>.

효과

미정

실패

미정

Result and effects

링크

Return Some for an integral value from -9223372036854775808 through 9223372036854775807. Return None() for a fraction or a value outside that range without changing the receiver.

Why

링크

Checked narrowing preserves the value instead of choosing a rounding or overflow policy implicitly.

Resolved contracts

링크

std.decimal →

Convert numeric values explicitly and without truncation

링크

규칙topaz.stdlib.contract.decimal-conversion.rule

Convert numeric values explicitly and without truncation

int.toDecimal converts every int value exactly and produces scale zero. Both signed 64 bit endpoints are representable. The conversion does not pass through float.

Decimal.toInt returns Some containing the same integer when the Decimal is integral and fits the integer conversion bounds.

A nonintegral Decimal or an integer outside the int range returns None(). Conversion does not round, truncate, wrap, saturate, or raise an arithmetic overflow fault. The original Decimal remains unchanged.

A value parsed from 1.000 is integral after normalization and converts to Some containing 1. A value parsed from 1.001 is nonintegral and returns None().

Existing int, float and BigInt values do not implicitly become Decimal values in arithmetic or comparisons. The module provides no direct float or BigInt conversion member.

For an exact BigInt conversion, format it with radix 10 and pass that text to Decimal.parse. To request an integral BigInt from a Decimal, pass its canonical text to BigInt.parse with radix 10. Fractional decimal text is rejected by that integer parser.

Converting through explicitly chosen text follows the corresponding text parser. Decimal.parse never recovers decimal digits that were lost in an earlier binary float calculation.

이유

Exact integer conversion and checked narrowing communicate different intentions. Option exposes fractions and overflow without selecting a rounding policy for the caller. Explicit text composition handles arbitrary precision integer exchange through the existing parsers without adding another conversion API.

예제 Convert both int endpoints and reject fractions or overflow →Convert int values to exact scale zero decimals →Exchange arbitrary precision integers through explicit decimal text →

Convert both int endpoints and reject fractions or overflow

링크

run · running · 검증 · 미실행

main.tpzConvert both int endpoints and reject fractions or overflow플레이그라운드 열기 →

import std.decimal { Decimal }
import std.test
import std.io
function read(text: string) -> Decimal {
let parsed: Option<Decimal> = Decimal.parse(text)
let value: Decimal = test.assertSome(parsed)
return value
}
for text in (["-9223372036854775808", "9223372036854775807", "-9223372036854775809", "9223372036854775808", "1.000", "1.001", "-1.001", "-0.000"]) {
let value: Decimal = read(text)
match (value.toInt()) {
case Some(integer) => io.writeLine("{integer}")
case None() => io.writeLine("not an int")
}
}
let large: Decimal = read("1000000000000000000000000000000")
let narrowed: Option<int> = large.toInt()
test.assertNone(narrowed)
io.writeLine(large.toString())

기대 출력종료 코드 0

-9223372036854775808
9223372036854775807
not an int
not an int
1
not an int
not an int
0
1000000000000000000000000000000

$ topaz run main.tpz · 대상 제품 5.21.3

기대 결과

실행을 마칩니다. 종료 코드 0.

표준 오류 출력 없음.

기대 표준 출력

-9223372036854775808
9223372036854775807
not an int
not an int
1
not an int
not an int
0
1000000000000000000000000000000

이 예제는 아직 실행하지 않았습니다.

Convert int values to exact scale zero decimals

링크

run · running · 검증 · 미실행

main.tpzConvert int values to exact scale zero decimals플레이그라운드 열기 →

import std.decimal { Decimal }
import std.test
import std.io
let integers: Array<int> = [-9223372036854775807 - 1, -1, 0, 1, 9223372036854775807]
for integer in (integers) {
let value: Decimal = integer.toDecimal()
let narrowed: Option<int> = value.toInt()
let recovered: int = test.assertSome(narrowed)
test.assertEq(recovered, integer)
io.writeLine("{value.toString()} {value.scale()}")
}

기대 출력종료 코드 0

-9223372036854775808 0
-1 0
0 0
1 0
9223372036854775807 0

$ topaz run main.tpz · 대상 제품 5.21.3

기대 결과

실행을 마칩니다. 종료 코드 0.

표준 오류 출력 없음.

기대 표준 출력

-9223372036854775808 0
-1 0
0 0
1 0
9223372036854775807 0

이 예제는 아직 실행하지 않았습니다.

Exchange arbitrary precision integers through explicit decimal text

링크

run · running · 검증 · 미실행

main.tpzExchange arbitrary precision integers through explicit decimal text플레이그라운드 열기 →

import std.decimal { Decimal }
import std.bigint { BigInt }
import std.test
import std.io
let parsedInteger: Option<BigInt> = BigInt.parse("123456789012345678901234567890", 10)
let integer: BigInt = test.assertSome(parsedInteger)
let parsedDecimal: Option<Decimal> = Decimal.parse(integer.toString(10))
let value: Decimal = test.assertSome(parsedDecimal)
io.writeLine(value.toString())
let parsedAgain: Option<BigInt> = BigInt.parse(value.toString(), 10)
let recovered: BigInt = test.assertSome(parsedAgain)
let equal = recovered == integer
io.writeLine("{equal}")
let parsedFraction: Option<Decimal> = Decimal.parse("1.5")
let fraction: Decimal = test.assertSome(parsedFraction)
let integral: Option<BigInt> = BigInt.parse(fraction.toString(), 10)
match (integral) {
case None() => io.writeLine("fraction rejected")
case Some(_) => io.writeLine("converted")
}

기대 출력종료 코드 0

123456789012345678901234567890
true
fraction rejected

$ topaz run main.tpz · 대상 제품 5.21.3

기대 결과

실행을 마칩니다. 종료 코드 0.

표준 오류 출력 없음.

기대 표준 출력

123456789012345678901234567890
true
fraction rejected

이 예제는 아직 실행하지 않았습니다.

문서 검색

Decimal.toInt

Declaration and parameters

사용 조건

수신자

매개변수 제약

결과

효과

실패

Result and effects

Why

Resolved contracts

Convert numeric values explicitly and without truncation

Convert numeric values explicitly and without truncation

이유

Convert both int endpoints and reject fractions or overflow

기대 결과

Convert int values to exact scale zero decimals

기대 결과

Exchange arbitrary precision integers through explicit decimal text

기대 결과

메뉴

Declaration and parameters

사용 조건

수신자

매개변수 제약

결과

효과

실패

Result and effects

Why

Resolved contracts

Related entries

Convert numeric values explicitly and without truncation

Convert numeric values explicitly and without truncation

이유

Convert both int endpoints and reject fractions or overflow

기대 결과

Convert int values to exact scale zero decimals

기대 결과

Exchange arbitrary precision integers through explicit decimal text

기대 결과