[转贴]size_t strlen1(const char *str)
{
const char *p = str;
while(*p) p ++;
return (size_t)(p - str);
}

size_t strlen2(const char *str)
{
unsigned v;
const char *p = str;
while(*p && ((unsigned)p & 3))
p ++;
if (*p == 0)
return (size_t)(p - str);
for (v = 0; !v; p += 4)
{
v = (*(unsigned*)p - 0x01010101) & 0x80808080;
if (v)
v &= ~*(unsigned*)p;
}
for (; (v & 0xff) == 0; p ++)
v >>= 8;
return (size_t)(p - str - 4);
}


本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/maozefa/archive/2011/03/10/6238782.aspx
作者是一个delphi老人（好像50多岁了！）