C#BigInteger和int如何节省内存? [英] C# BigInteger and int How to save memory?

问题描述

我正在测试矩阵是否在每行中都有素数.

I am testing a matrix if it has a prime number in every line.

MR表示应使用Miller Rabin算法.如果其为假，则仅尝试除数直到sqrt(n).如果Vansor在每个选中的行中都找到了素数，则为true；如果在实际选中的行中找到了素数，则vanoszlop为true.

The MR means that it should use the Miller Rabin algorithm. If its false it simply tries the divisors up to sqrt(n). Vansor is true if it has found a prime in every checked row, vanoszlop is true if it has found a prime in the actually checked row.

我的问题是:仅当tryParse为true时，才可以通过不同时创建int和BigInteger值来节省内存吗?我的意思是

My question is: Is it possible to save the memory by not creating both the int and BigInteger values only if the tryParse is true? I mean something like

if (int.tryParse(akt, out new int szam))

像这样可能吗? (以及BigInteger未签名时需要占用多少内存?)

Is something like this possible? (and how much memory does a BigInteger take when its not signed?)

    akt = Console.ReadLine();
    int szam; BigInteger szambig;

    if (int.TryParse(akt, out szam))
    {
       if (MR)  {
          if (MilRab(szam))
          { vansor = true; vanoszlop = true; } }

          else if (Prim(szam))
          { vansor = true; vanoszlop = true; }
    }
    else if (BigInteger.TryParse(akt, out szambig))
    {
       if (MR) {
          if (MilRab(szam))
          { vansor = true; vanoszlop = true; } }

       else if (Prim(szam))
       { vansor = true; vanoszlop = true; }
    }

推荐答案

我不确定.Net IL如何优化内存，但是一般而言，本地值"类型(与引用"类型相对)是100％的.放在堆栈上. IE，您只会通过不实例化一个整数来保存它占用的〜4个字节，并且仅在该调用的整个生命周期内保存.退出该功能后，将清除堆栈.

I'm not 100% sure on how .Net IL optimizes memory, but in general local "value" type (as opposed to "reference" types) are kept on the stack. IE, you would only save the ~4 bytes that an integer takes up by not instantiating it, and only for the lifetime of that one call. Once you exit the function, the stack is cleared.

结构是值"类型，也放置在堆栈中.它们为所有其他值类型&保留内存.根据需要引用指针.无论签名"为真还是假，BigInteger的大小都是相同的.

Structures are "value" types, and are also placed on the stack. They reserve memory for all other value types & reference pointers as needed. The size of a BigInteger is the same whether or not "Signed" is true or false.

我想我真正的问题是:为什么记忆力困扰?对于您拥有的代码示例，您将占用几十个字节的内存，当方法退出时，这些内存将全部释放.

I suppose my real question is: why the memory obsession? With the code example you have, you'll take a few dozen bytes of memory that will all be freed up when the method exits.

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