This function queries the length of the text string in a dialog item, not including any null termination character.

#define INCL_WINDIALOGS /* Or use INCL_WIN, INCL_PM, Also in COMMON section */
#include <os2.h>

HWND     hwndDlg;  /*  Parent-window handle. */
ULONG    idItem;   /*  Identity of the child window whose text is to be queried. */
LONG     lRetLen;  /*  Length of text. */

lRetLen = WinQueryDlgItemTextLength(hwndDlg,
            idItem);