我正在尝试为在Win XP上运行的C程序编写一个byteswap例程.我正在使用Visual Studio 2008编译.这就是我想出的：
int byteswap(int v) // This is good
{
return _byteswap_ulong(v);
}
double byteswap(double v) // This doesn't work for some values
{
union { // This trick is first used in Quake2 source I believe :D
__int64 i;
double d;
} conv;
conv.d = v;
conv.i = _byteswap_uint64(conv.i);
return conv.d;
}
还有一个测试功能：
void testit() {
double a,b,c;
CString str;
for (a = -100; a < 100; a += 0.01) {
b = byteswap(a);
c = byteswap(b);
if (a != c) {
str.Format("%15.15f %15.15f %15.15f",a,c,a - c);
}
}
}
获取这些数字不匹配：
-76.789999999988126 -76.790000000017230 0.000000000029104 -30.499999999987718 -30.499999999994994 0.000000000007276 41.790000000014508 41.790000000029060 -0.000000000014552 90.330000000023560 90.330000000052664 -0.000000000029104
这是在阅读完之后：
How do I convert between big-endian and little-endian values in C++?
Little Endian – Big Endian Problem
你不能使用<<和>>顺便说一下(除非我弄错了？)
