如何获得一个变量的各字节的值？ [英] How to get the value of individual bytes of a variable?

问题描述

我知道，让一个变量的类型使用的字节数，你可以使用的sizeof（INT）的实例。你如何使用的各个字节的值，当您存储与该变量的类型是多少？ （即 INT X = 125 ）

I know that to get the number of bytes used by a variable type, you use sizeof(int) for instance. How do you get the value of the individual bytes used when you store a number with that variable type? (i.e. int x = 125.)

推荐答案

您可以通过使用一些指针运算得到字节：

You can get the bytes by using some pointer arithmetic:

int x = 12578329; // 0xBFEE19
for (size_t i = 0; i < sizeof(x); ++i) {
  // Convert to unsigned char* because a char is 1 byte in size.
  // That is guaranteed by the standard.
  // Note that is it NOT required to be 8 bits in size.
  unsigned char byte = *((unsigned char *)&x + i);
  printf("Byte %d = %u\n", i, (unsigned)byte);
}

在我的机器上（英特尔的x86-64），输出是：

On my machine (Intel x86-64), the output is:

Byte 0 = 25  // 0x19
Byte 1 = 238 // 0xEE
Byte 2 = 191 // 0xBF
Byte 3 = 0 // 0x00

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