用C铸造浮到INT（按位） [英] Casting float to int (bitwise) in C

问题描述

或编译运行转换）？

编辑＃1：

我有以下功能，但它在某些情况下会失败：

I have to following function but it fails in some cases:

输入：INT X（包含IEEE 754格式的32位单precision号）

Input: int x (contains 32 bit single precision number in IEEE 754 format)

  if(x == 0) return x;

  unsigned int signBit = 0;
  unsigned int absX = (unsigned int)x;
  if (x < 0)
  {
      signBit = 0x80000000u;
      absX = (unsigned int)-x;
  }

  unsigned int exponent = 158;
  while ((absX & 0x80000000) == 0)
  {
      exponent--;
      absX <<= 1;
  }

  unsigned int mantissa = absX >> 8;

  unsigned int result = signBit | (exponent << 23) | (mantissa & 0x7fffff);
  printf("\nfor x: %x, result: %x",x,result);
  return result;

编辑＃2：

另外需要的帮助：<一href=\"http://cs.stackexchange.com/questions/3484/converting-function-to-bitwise-only\">http://cs.stackexchange.com/questions/3484/converting-function-to-bitwise-only

推荐答案

C有联盟来处理这种类型的视图数据：

C has the "union" to handle this type of view of data:

typedef union {
  int i;
  float f;
 } u;
 u u1;
 u1.f = 45.6789;
 /* now u1.i refers to the int version of the float */
 printf("%d",u1.i);

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