Function CompareVersion

source/util.cpp:3153–3191

int CompareVersion(LPCTSTR a, LPCTSTR b)
{
	while (*a || *b)
	{
		// 1.1-a001 < 1.1 = 1.1.0 = 1.1.0+foo
		LPTSTR pa, pb;
		int ia = _tcstol(a, &pa, 10);
		int ib = _tcstol(b, &pb, 10);
		// If *pa is not in the set .-+\0, this component is non-numeric (and not empty).
		// Treat non-numeric as greater than numeric (but assume any absent component is 0).
		if (!_tcschr(_T(".-+"), *pa)) ia = INT_MAX; else a = pa;
		if (!_tcschr(_T(".-+"), *pb)) ib = INT_MAX; else b = pb;
		if (ia < ib) return -1;
		if (ia > ib) return  1;
		// They are either equal or both non-numeric.
		if (*a == '.' || *b == '.')
		{
			if (*a == '.') ++a;
			if (*b == '.') ++b;
			continue; // On to the next component.
		}
		// Give -pre-release lower precedence.
		if (*a == '-' && *b != '-') return -1;
		if (*b == '-' && *a != '-') return  1;
		for (;; ++a, ++b)
		{
			auto ac = *a == '+' || *a == '.' ? '\0' : *a; // Ignore any + suffix (treat as terminator).
			auto bc = *b == '+' || *b == '.' ? '\0' : *b;
			if (ac != bc) return ac < bc ? -1 : 1;
			if (!ac) // End of both components.
			{
				if (*a == '.' || *b == '.')
					break; // Try to compare the next component as numeric.
				return 0; // Both reached the end; a and b are equal.
			}
		}
	}
	return 0;
}