warning C4146: unary minus operator applied to unsigned type, result still unsigned

Question

1	char* StringDump::SaveString(const char* s, int len) {
2	if (len == -1)
3	len = lstrlen(s);
4	if (block_pos+len+1 > block_size) {
5	char* newnew_block = new char[block_size = max(block_size, len+1+sizeof(char*))];
6	_RPT0(0,"StringDump: Allocating new stringblock.\r\n");
7	*(char**)new_block = current_block;   // beginning of block holds pointer to previous block
8	current_block = new_block;
9	block_pos = sizeof(char*);
10	}
11	char* result = current_block+block_pos;
12	memcpy(result, s, len);
13	result[len] = 0;
14	block_pos += (len+sizeof(char*)) & -sizeof(char*); // Keep 32bit aligned
15	return result;
16	}

Line 14 in the code quote is the one with the warning.

warning C4146: unary minus operator applied to unsigned type, result still unsigned

Answer 1

Here's the answer but I don't know how to apply it to my code.
link

Answer 2

Select one of these:

 

    block_pos += (len+sizeof(char*)) & -int(sizeof(char*));

 

or

 

#pragma warning( disable : 4146 )

    block_pos += (len+sizeof(char*)) & -sizeof(char*);

#pragma warning( default : 4146 )

Answer 3

Viorel_ said:

Select one of these:

 

    block_pos += (len+sizeof(char*)) & -int(sizeof(char*));

 

That worked. Thank you.