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VB.NET 中的除法

发布于 2024-10-05 08:31:52 字数 111 浏览 3 评论 0原文

VB.NET 中的除法 / 和 \ 有什么区别？

我的代码根据我使用的代码给出了非常不同的答案。我以前见过这两种，但我一直不知道有什么区别。

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蓝咒 2024-10-12 08:31:53

有两种除法。快法和慢法。许多编译器试图诱骗您以更快的方式完成此操作。 C# 就是其中之一，试试这个：

using System;

class Program {
    static void Main(string[] args) {
        Console.WriteLine(1 / 2);
        Console.ReadLine();
    }
}

输出：0

您对这个结果满意吗？当表达式的左侧和右侧都是整数时，这是技术上正确的、记录的行为。这会进行快速的整数除法。处理器上的 IDIV 指令，而不是（臭名昭著的）FDIV 指令。也与所有花括号语言的工作方式完全一致。但绝对是 SO 中“发生了什么事”问题的主要来源。为了获得满意的结果，您必须执行以下操作：

    Console.WriteLine(1.0 / 2);

输出：0.5

左侧现在是双精度型，强制进行浮点除法。计算器显示的结果类型。调用 FDIV 的其他方法是将右侧设为浮点数或将操作数之一显式转换为 (double)。

VB.NET 不是这样工作的，/ 运算符始终是浮点除法，无论类型如何。有时您确实想要整数除法。这就是 \ 的作用。

There are two ways to divide numbers. The fast way and the slow way. A lot of compilers try to trick you into doing it the fast way. C# is one of them, try this:

using System;

class Program {
    static void Main(string[] args) {
        Console.WriteLine(1 / 2);
        Console.ReadLine();
    }
}

Output: 0

Are you happy with that outcome? It is technically correct, documented behavior when the left side and the right side of the expression are integers. That does a fast integer division. The IDIV instruction on the processor, instead of the (infamous) FDIV instruction. Also entirely consistent with the way all curly brace languages work. But definitely a major source of "wtf happened" questions at SO. To get the happy outcome you would have to do something like this:

    Console.WriteLine(1.0 / 2);

Output: 0.5

The left side is now a double, forcing a floating point division. With the kind of result your calculator shows. Other ways to invoke FDIV is by making the right-side a floating point number or by explicitly casting one of the operands to (double).

VB.NET doesn't work that way, the / operator is always a floating point division, irrespective of the types. Sometimes you really do want an integer division. That's what \ does.

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何以心动 2024-10-12 08:31:53

10 / 3 = 3.333
10 \ 3 = 3 (the remainder is ignored)

10 / 3 = 3.333
10 \ 3 = 3 (the remainder is ignored)

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反目相谮 2024-10-12 08:31:53

/ Division
\ Integer Division

/ Division
\ Integer Division

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梅倚清风 2024-10-12 08:31:53

10 / 3 = 3.33333333333333, assigned to integer = 3
10 \ 3 = 3, assigned to integer = 3
20 / 3 = 6.66666666666667, assigned to integer = 7
20 \ 3 = 6, assigned to integer = 6

上述代码：

Dim a, b, c, d As Integer
a = 10 / 3
b = 10 \ 3
c = 20 / 3
d = 20 \ 3

Debug.WriteLine("10 / 3 = " & 10 / 3 & ", assigned to integer = " & a)
Debug.WriteLine("10 \ 3 = " & 10 \ 3 & ", assigned to integer = " & b)
Debug.WriteLine("20 / 3 = " & 20 / 3 & ", assigned to integer = " & c)
Debug.WriteLine("20 \ 3 = " & 20 \ 3 & ", assigned to integer = " & d)

10 / 3 = 3.33333333333333, assigned to integer = 3
10 \ 3 = 3, assigned to integer = 3
20 / 3 = 6.66666666666667, assigned to integer = 7
20 \ 3 = 6, assigned to integer = 6

Code for the above:

Dim a, b, c, d As Integer
a = 10 / 3
b = 10 \ 3
c = 20 / 3
d = 20 \ 3

Debug.WriteLine("10 / 3 = " & 10 / 3 & ", assigned to integer = " & a)
Debug.WriteLine("10 \ 3 = " & 10 \ 3 & ", assigned to integer = " & b)
Debug.WriteLine("20 / 3 = " & 20 / 3 & ", assigned to integer = " & c)
Debug.WriteLine("20 \ 3 = " & 20 \ 3 & ", assigned to integer = " & d)

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