(某数&0x04)等价于((某数&0x4)==0x4)

类似汇编的test

#include<stdio.h>
#include<string.h>
void fun(int s)
{
 printf("- is hex:%x dec:%d\n",s,s);
 if(s&0x4)printf("-&04\n");
  if(s&0x2)printf("-&2\n");
  if((s&0x4)==0x4)printf("(-&04)==0x4\n");
  if((s&0x4)==1)printf("(-&04)==1\n");
  if((s&0x01)==1)printf("(-&0x01)==1\n");
}
int main()
{

  int s=0x4;
  fun(s);
  printf("==============\n");
  fun(0x46);
  printf("==============\n");
  fun(0xf2);
  printf("==============\n");
  fun(0xf7);
  return 0;
}

- is hex:4 dec:4

-&04

(-&04)==0x4

==============

- is hex:46 dec:70

-&04

-&2

(-&04)==0x4

==============

- is hex:f2 dec:242

-&2

==============

- is hex:f7 dec:247

-&04

-&2

(-&04)==0x4

(-&0x01)==1