void _memmove(void * src, void * des, int n)
{
unsigned char *s;
unsigned char *t;
assert(src!=NULL);
assert(des!=NULL);
if(n<=0 || des==src)return;
if(des>src)
{
s = (unsigned char*)src+n-1;
t = (unsigned char*)des+n-1;
while(n--)*t-- = *s--;
}else /* des<src */
{
s = (unsigned char*)src;
t = (unsigned char*)des;
while(n--)*t++ = *s++;
}
}
全局变量放在数据段里(位置固定,程序加载时刻决定),局部变量放在堆栈里(位置随机,运行时刻决定),一般编译器好象都这样干. |
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