Prototype and description of the function karttk2geo()

(Function of the unlock requiring group "Map calculations")


Determination of the corner coordinate of a topographic map.

Prototype of the DLL function in C++ syntax (attend lower case!):
extern "C" __declspec(dllimport) unsigned long __stdcall karttk2geo(
     unsigned short nTK25,
     double *nGeoLon,
     double *nGeoLat);

Prototype of the DLL function in Visual Objects syntax:
_DLL function karttk2geo(;
     nTk25 as word,;                       // 2 Byte
     nGeoLon ref real8,;                   // 4 Byte
     nGeoLat ref real8);                   // 4 Byte
as logic pascal:geodll32.karttk2geo        // 4 Byte

The function returns the hitting corner coordinate of the left lower corner
of an official topographic map of the Federal Republic of Germany on a scale
of 1:25000 (TK25, ordnance map) to the calling program. Since all TK25 are
exactly 6 minutes wide on the longitude and exactly 10 minutes wide on the
latitude, the hitting corner coordinates of the other map corners can be
calculated easy.

The function returns the geographic coordinate nGeoLon and nGeoLat in
[degrees] notation (ggg.nnn) by reference. The degrees portion (g) is
integer, the minute and second portions are represented as decimal fraction
of a degree (n).

The parameters are passed and/or returned as follows:
nTK25       Number of the TK25.

nGeoLon     Geographic longitude of the left lower corner in [degrees]
(ref)       notation as reference.

nGeoLat     Geographic latitude of the left lower corner in [degrees]
(ref)       notation as reference.

returnVal   In case of an error the function returns FALSE, otherwise TRUE.

This function is a component of the unlock requiring function group
"map calculations". It is unlocked for unrestricted use together with the
other functions of the group by passing the unlock parameters, acquired
from the software distribution company, trough the function setunlockcode().
Without unlocking only a few function calls for test purposes (shareware
principle) are possible.