字符串处理的一些题

int removesubstr(char *s, char *t)
{
char *dst, *sp, *tp;
int find = 0;
dst = s;
while (*s)
{
sp = s;
tp = t;
while (*tp && (*sp == *tp))
{
sp++;
tp++;
}
if (!*tp)
{
find = 1;
break;
}
s++;
}
if (find == 1)
{
while ((*s++ = *sp++) != '\0');
}
s = dst;
return find;
}

void * my_memcpy(void* dest, void* source, size_t count)
{
char *ret = (char *)dest;
char *dest_t = ret;
char *source_t = (char *)source;

while (count--){
*dest_t++ = *source_t++;
}
return ret;
}

void * my_memmove(void *dst,const void *src,int count)
{
char *ret;
char *dst_t;
char *src_t;

ret = (char *)dst;

if ((unsigned char*)dst <= (unsigned char*)src
|| (unsigned char *)dst >= ((unsigned char *)src + count))
{
dst_t = (char *)dst;
src_t = (char *)src;
while (count--)
{
*dst_t++ = *src_t++;
}
}
else
{
dst_t = (char *)dst + count - 1;
src_t = (char *)src + count - 1;
while (count--)
{
*dst_t-- = *src_t--;
}
}
return ret;
}