对于一些重新presentation [英] Regarding number representation

问题描述

我如何找到适合的系统，我就数重新presentation？

How do I find the representation of a Number for the system I am on?

推荐答案

如再presentation（字的大小，two's-与补码与符号 - 幅度）和字节顺序建筑的问题最好用硬件回答和/或操作系统和/或编译器文档。

Architectural questions such as representation (word size, two's- vs. one's-complement vs. sign-magnitude) and endianness are best answered with hardware and/or OS and/or compiler documentation.

您可以使用双关语的类型来检查一个值的单个字节：

You can use type punning to examine the individual bytes of a value:

T value = ...; // for some numeric type T (int, short, long, double, float, etc.)
unsigned char *p = (unsigned char*) &value;
size_t i;

printf("%10s%8s\n", "address", "value");
printf("%10s%8s\n", "-------", "-----");
for (i = 0; i < sizeof value; i++)
  printf("%10p%8x\n", p+i, (unsigned int) p[i]);

有关大端与小端，你可以不喜欢

For big- vs. little-endian, you could do something like

unsigned int value = 0x01;
unsigned char *p = (unsigned char *) &value;
if (p[0] == 1)
  printf("Little-endian\n");
else if (p[sizeof value - 1] == 1)
  printf("Big-endian\n");
else
  printf("Weird\n");

更好地RTM，虽然。

Better to RTM, though.

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