I revised the implementation of alphanumeric ordering by removing handling of decimal and negative numbers so that the period, dash, and underscore characters may be used as separators in numeric text. In addition, numeric text may contain a thousands separator, such as a comma or a space.
This program can be downloaded from TextANSort.zip (1,013 KB). Right click on this link, select "Save link as," choose a location, and click on the Save button.
Alphanumeric ordering is now in several classes. Here is part of it.
// Actions: Limits comparison results to -1, 0 or 1 since
// some sorting functions may expect these values.
int CStringOrder::LimitResult (int nTest) const
{
if (nTest < 0) {
return -1;
}
else if (nTest == 0) {
return 0;
}
else {
return 1;
}
} // LimitResult
// Actions: Simple alphanumeric comparisons.
// Notes: Requires that there be a digit in the same starting place in
// each filename. Limited to numbers smaller than 2^31,
// about two billion (2,147,483,647).
int CStringSANOrder::CompareStrings (LPCTSTR pszItem1, LPCTSTR pszItem2) const
{
if (pszItem1 == nullptr || pszItem2 == nullptr) return 0;
register LPCTSTR psz1{ pszItem1 };
register LPCTSTR psz2{ pszItem2 };
int nTest{};
while (*psz1 != _T('\0') && *psz2 != _T('\0')) {
if (::_istdigit (*psz1) && ::_istdigit (*psz2)) { // generic for isdigit
nTest = ::_ttoi (psz1) - ::_ttoi (psz2); // generic for atoi
if (nTest != 0) {
return LimitResult (nTest);
}
// Moves past the numbers.
while (::_istdigit (*psz1)) ++psz1;
while (::_istdigit (*psz2)) ++psz2;
}
else {
#if defined(LOCALEORDER)
// locale caseless match
nTest = ::_tcsnicoll (psz1, psz2, 1); // generic for _strnicoll
#else
// caseless match
nTest = ::_totlower (*psz1) - ::_totlower (*psz2); // generic for tolower
#endif
if (nTest != 0) {
return LimitResult (nTest);
}
++psz1;
++psz2;
}
}
nTest = *psz1 - *psz2; // One string has ended.
return LimitResult (nTest);
} // CompareStrings
The zip file for alphabetic and simple alphanumeric ordering can be downloaded from StringSANOrder.zip (3 KB). Right click on this link, select "Save link as," choose a location, and click on the Save button.
This source code may be used in any program, including commercial ones. Please credit me in your program's documentation.
Last updated: 26-June-2026
