初夏小談:シミュレーションmemcpy,memmove

menmcpyコピーは、文字列に限らず文字型、カスタム構造体などであってもよい

#include

//    memcpy
void* Memcpy(void* dest, void* src, size_t count)
{
	void* ret = dest;
	while (count--)
	{
		*(char*)dest = *(char*)src;
		dest = (char*)dest + 1;
		src = (char*)src + 1;
	}
	return ret;
}

//    memmove
void* Memmove(void* dest, void* src, size_t count)
{
	void* ret = dest;
	if (dest <= src || (char*)dest >= (char*)src + count)
	{
		while (count--)
		{
			*(char*)dest = *(char*)src;
			dest = (char*)dest + 1;
			src = (char*)src + 1;
		}
	}
	else
	{
		dest = (char*)dest + count - 1;
		src = (char*)src + count - 1;
		while (count--)
		{
			*(char*)dest = *(char*)src;
			dest = (char*)dest + 1;
			src = (char*)src + 1;
		}
	}
	return ret;
}

int main()
{
	char arr[] = "2jin2gmin8gzhen";
	char arr1[1024] = "0";
	int x = strlen(arr);
	char* p=Memcpy(arr1, arr, x);
	printf("%s
", p);
	printf("%s
", arr);
	char* p1 = Memmove(arr1, arr, x);
	printf("%s
", p1);
	printf("%s
", arr1);
	system("pause");
	return 0;
}

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