c# - implementing for loop to check data -

i want able retrieve template (fingerprint) database , compare onto current template captured using fingerprint reader. using web service not working.

public fgrtemplate stuverifications(int id)         {             cn.open();             sqlcommand com = new sqlcommand("select template tblfingerprint id = '" + id + "'", cn);             //com.parameters.addwithvalue("id", i);             sqldatareader sd = com.executereader();             while (sd.read())             {                 fgrtemplate fingerprint = new fgrtemplate()                 {                     id = sd.getint32(0),                     studentid = sd.getint32(1),                     description = sd.getstring(2)                     //template = sd.getbyte(3)                  };                 cn.close();                 return fingerprint;              }              cn.close();             return new fgrtemplate(); 

the code below matches 2 template

//3rd step - match against registered template                       string[] fingerpos_str = new string[]                                            {                                               "unknown finger",                                               "right thumb",                                               "right index finger",                                               "right middle finger",                                               "right ring finger",                                               "right little finger",                                               "left thumb",                                               "left index finger",                                               "left middle finger",                                               "left ring finger",                                               "left little finger"};                      int32 err;                     sgfpmfingerposition finger_pos = sgfpmfingerposition.fingpos_uk;                     bool finger_found = false;                      sgfpmansitemplateinfo sample_info = new sgfpmansitemplateinfo();                     foreach (fgrtemplate m_storedtemplate in studentverifications(s.id))                       //err = m_fpm.getansitemplateinfo(m_storedtemplate, sample_info);                      (int = 0; < sample_info.totalsamples; i++)                     {                         bool matched = false;                         err = m_fpm.matchansitemplate(m_storedtemplate, i, m_vrfmin, 0, m_securitylevel, ref matched);                         if (matched)                         {                             finger_found = true;                             finger_pos = (sgfpmfingerposition)sample_info.sampleinfo[i].fingernumber;                             // break;                         }                     }                      if (err == (int32)sgfpmerror.error_none)                     {                         if (finger_found)                             richtextbox1.text = "the matched data found. finger position: " + fingerpos_str[(int32)finger_pos];                         else                             richtextbox1.text = "cannot find matched data";                     }                     else                         richtextbox1.text = "matchansitemplate() error : " + err; 

i want able check each row in database having difficulties in doing so. how implement loop in situation.

many thanks

use ienumerable this:

public ienumerable<fgrtemplate> stuverifications(int id)             {                 cn.open();                 sqlcommand com = new sqlcommand("select template tblfingerprint id = '" + id + "'", cn);                 //com.parameters.addwithvalue("id", i);                 sqldatareader sd = com.executereader();                 while (sd.read())                 {                     fgrtemplate fingerprint = new fgrtemplate()                     {                         id = sd.getint32(0),                         studentid = sd.getint32(1),                         description = sd.getstring(2)                         //template = sd.getbyte(3)                      };                     yield return fingerprint;                  }                  cn.close(); 

this return collection of fgrtemplates (one each row) can foreach through after.

then go through each template (note guessing @ how method want loop works, may not right):

foreach(fgrtemplate t in stuverifications(id)) { err = m_fpm.matchansitemplate(t, i, m_vrfmin, 0, m_securitylevel, ref matched); if (matched)       display student name   else       error message }