int m_strstr(const char*dst,const char*sub)
{
if (dst == NULL || sub == NULL)
return NULL;
int d_length = strlen(dst) + 1;
int s_length = strlen(sub) + 1;
int dst_index;
int sub_index;
int j;
for (dst_index = 0; dst_index < d_length; ++dst_index)
{
sub_index = 0;
if (dst[dst_index] == sub[sub_index])
{
j = dst_index;
while (dst[j] == sub[sub_index])
{
++sub_index;
++j;
if (sub_index == (s_length - 1))
return dst_index;
}
}
}
return -1;
}
char* m_strcpy(char* dst, const char* src)
{
if (dst == NULL || src == NULL)
return NULL;
char* dst_t = dst;
while (*dst_t++ = *src++);
return dst;
}
void* m_memmove(void* dst,const void* src,int count)
{
if (dst == NULL || src == NULL)
return NULL;
char* dst_t = (char*)dst;
char* src_t = (char*)src;
int s_length = strlen(src_t) + 1;
if ((int)dst < (int)src || (int)dst >(int)src + s_length)
{
while (count--)
{
*dst_t++ = *src_t++;
}
}
else
{
while (count)
{
*(dst_t + count) = *(src_t + count);
count--;
}
}
return dst;
}
int m_strcmp(const char* dst, const char* src)
{
assert(dst == NULL);
assert(src == NULL);
while ((*dst++ == *src++)&&(*dst != '\0')&&(*src != '\0'));
return *dst - *src;
}