Both GetSaveAsBox and GetOpenBox are documented in Help:Programming:Origin C Language Reference:Global Functions, but I have written this example that I hope will help you with your need.
void test()
{
string strFilename = GetOpenBox("*.*");
if(strFilename.IsEmpty()) // user cancel
return;
string strPath = GetFilePath(strFilename);
string strName = GetFileName(strFilename);
// remove extension from file name
int nExtPos = strName.Find('.');
if(nExtPos > 0)
strName = strName.Left(nExtPos);
// do other things in your code
string strSaveName = GetSaveAsBox("*.opj", strPath, strName);
printf("User has choosen\n%s\n",strSaveName);
}
You should not need to use LT_Execute to call LabTalk when Origin C functions are already available.
CP