php uses txt text files as database programs_PHP tutorial

define ("tblPath",".");
define ("exten",".php");
define ("fileHead","This file only for class txtTbl");
class txtTbl {
var $innerName=""; //Database name
var $innerCount; //Number of database records
var $innerFields; //Database field list array
var $inner_F_Count; //Number of database fields
var $fullName; //Complete file name
var $isModify = false; //Whether the current record has been modified
var $fileModify = false; //Whether the database has been modified
var $innerRecorders; //Database record array
var $curLine; //Current record number
var $curArray; //Current line Array
var $stringDel; //Save deleted records
var $sprt1; //Separator between database records
var $sprt2; //Separator between database fields
var $innerBof = true;
var $innerEof = false;

function create($tblName,$fields,$sprt1="<---txtTbl--->n" ,$sprt2="<---txtTbl--->"){
if (empty($tblName)){
echo "The textDateBase file name not appoint.";
return false ;
}
$fullName = tblPath.$tblName.exten;
if (file_exists($fullName)){
echo "The textDateBase file is already exist.";
return false;
}
if(empty($fields)){
echo "The fields list Array is invalid.";
return false;
}
$cont = implode($sprt2 ,$fields);
$cont = fileHead."n".$cont;
$fp = fopen($fullName,"w");
fwrite($fp,$cont);
fclose($fp);
return true;
}

  function drop($tblName,$sprt1="<---txtTbl--->n",$sprt2="<---txtTbl--->"){
 if (empty($tblName)){
  echo "The textDateBase file name not proveid.";
  return false;
 }
 if (!empty($this->innerName)){
  echo "Current file not closed,Please close it and try again.";
  return false;
 }
 $fullName = tblPath.$tblName.exten;
    if (!file_exists($fullName)){
  echo "The textDateBase file not exist.";
  return false;
 }
 $fp = fopen($fullName,"r");
 if (!feof($fp)){
  $readFromFile = fgets($fp);
 }
 if ($readFromFile!=fileHead."n"){
  fclose($fp);
  echo "not a valid textDataBase file.(the head is invalid.)"."n";
  return false;
 }
 $readFromFile = "";
 if (!feof($fp)) $readFromFile.= fgets($fp);
 fclose($fp);
 $readFromFile = trim($readFromFile);
 if (empty($readFromFile)){
  echo "not a valid textDataBase file.(can't find fields define.)";
  return false;
 }
 $cont = fileHead."n".$readFromFile;
 $fp = fopen($fullName,"w");
 fwrite($fp,$cont);
 fclose($fp);
 return true;
  }
 
 
  function open($tblName,$sprt1="<---txtTbl--->n",$sprt2="<---txtTbl--->"){
 if (empty($tblName)){
  echo "The textDateBase file name not proveid.";
  return false;
 }
 if (!empty($this->innerName)){
  echo "Current file not closed,Please close it and try again.";
  return false;
 }
 $this->fullName = tblPath.$tblName.exten;
    if (!file_exists($this->fullName)){
  echo "The textDateBase file not exist.";
  return false;
 }
 $fp = fopen($this->fullName,"r");
 if (!feof($fp)){
  $readFromFile = fgets($fp);
 }
 if ($readFromFile!=fileHead."n"){
  fclose($fp);
  echo "not a valid textDataBase file.(the head is invalid.)"."n";
  return false;
 }
 $readFromFile = "";
 while (!feof($fp)) $readFromFile.= fgets($fp);
 fclose($fp);
 $readFromFile = trim($readFromFile);
 if (empty($readFromFile)){
  echo "not a valid textDataBase file.(can't find fields define.)";
  return false;
 }
    $this->innerRecorders = explode($sprt1,$readFromFile);
 $this->innerCount = count($this->innerRecorders) - 1;
    $this->innerFields = explode($sprt2,$this->innerRecorders[0]);
    $this->innerFieldsCount = count($this->innerFields);

 $this->innerName = $tblName;
 $this->sprt1 = $sprt1;
 $this->sprt2 = $sprt2;

 if ($this->innerCount==0){
  $this->curLine = 0;
  $this->innerEof = true;
 }else{
  $this->curLine = 1;
//  if ($this->innerCount==1) $this->innerEof = true;
        if (!$this->initRec()) return false;
 }

 return true;
  }

  function close(){
 if (empty($this->innerName)) return true;
 //save modify
 $isModify= false;
    if ($this->isModify){
  $this->saveModify();
  $isModify= true;
 }
 if(isset($this->stringDel)){
  $isModify= true;
  $delNo= explode(",",$this->stringDel);
  foreach($delNo as $no){
   $no= (integer) $no;
   unset($this->innerRecorders[$no]);
  }
 }
 if ($isModify||$this->fileModify){
  $recorders= implode($this->sprt1,$this->innerRecorders);
  $recorders= fileHead."n".$recorders;
  $fp = fopen($this->fullName,"w");
  fwrite($fp,$recorders);
  fclose($fp);
 }
 $this->innerName="";
 unset($this->innerRecorders);
 unset($this->curArray);
  }

  function next(){
   if ((!$this->innerEof)&&(!empty($this->innerName))){
    if($this->curLine==$this->innerCount){
     $this->innerEof = true;
     return true;
    }
    $this->saveModify();
    $this->curLine++;
    if ($this->innerBof) $this->innerBof = false;
    $this->initRec();
   }
   return false;
  }
 
  function prev(){
   if ((!$this->innerBof)&&(!empty($this->innerName))){
    $this->saveModify();
    $this->curLine--;
    if ($this->curLine == 1)
     $this->innerBof = true;
    if ($this->innerEof) $this->innerEof = false;
    $this->initRec();
   }
  }

  function first(){
    if ($this->innerBof||empty($this->innerName))
  return false;
    $this->saveModify();
 $this->curLine = 1;
 $this->innerBof= true;
 $this->innerEof = false;
 $this->initRec();
 
  }
 
  function end(){
    if ($this->innerEof||empty($this->innerName))
  return false;
    $this->saveModify();
 $this->curLine = $this->innerCount;
 $this->innerEof= true;
 $this->innerBof = false;
 $this->initRec();
 
  }
 
  function eof(){
   if (empty($this->innerName)){
    return false;
   }else return $this->innerEof;
  }

  function bof(){
   if (empty($this->innerName)){
    return true;
   }else return $this->innerBof;
  }

  function recNo(){
   return $this->curLine;
  }

  function recCount(){
   return $this->innerCount;
  }

  function fieldsCount(){
   if (empty($this->innerName)){
    return false;
   }else return $this->inner_F_Count;
  }

  function getValue($field){
 if ($this->curLine==0||empty($this->innerName)){
  echo "Can't read current record,maybe not in use or no record.";
  return false;
 }
 $field= $this->chkField($field);
    if ($field==-1){
  return false;
 }
 return $this->curArray[$field];
  }

 
  function setValue($field,$value){
    if ($this->curLine==0||empty($this->innerName)){
  echo "Can't read current record,maybe not in use or no record.";
  return false;
 }
 $field= $this->chkField($field);
 if ($field==-1){
  return false;
 }
 $this->curArray[$field]= $value;
 $this->modify= true;
  }
 
  function display($shownon=0,$sprt1="",$sprt2="",$sprt3="",$sprt4=""){
 echo $sprt3;
 foreach($this->curArray as $v){
  if($shownon==1&&empty($v)) $v= "noValue";
  echo $sprt1.$v.$sprt2;
 }
 echo $sprt4;
  }

  function location($field,$keyValue){
    $field=$this->chkField($field);
 if ($field==-1) return false;
 for($i=$this->curLine;$i<=$this->innerCount;$i++){
  if($this->curArray[$field]==$keyValue){
   return true;
  }
  $this->next();
 }
 return false;
  }
 
  function del($recNo=-1){
 if($this->curLine==0) return false;
 $vartype= gettype($recNo);
 if($vartype!="integer"){
  echo "del error:check ur para type.";
  return false;
 }
    if ($recNo==-1){
  $recNo=$this->curLine;}
 elseif ($recNo>$this->innerCount||$recNo<1){
  echo "del error:out over the rang.";
  return false;
 }
 if (!$this->chkDel($recNo)){
  if(isset($this->stringDel)){
   $this->stringDel.=(','.$recNo);
  }else $this->stringDel = (string) $recNo;
 }else return false;
  }
  
  function append($fields=""){
 $this->saveModify();
 for($i=1;$i<=$this->innerFieldsCount;$i++)
  $newRec[] = "";
    if(!empty($fields)){
  foreach($fields as $k=>$v){
   $k= $this->chkField($k);
   if ($k==-1){
    return false;
   }
            $newRec[$k]= $v;
  }
 }
 $this->innerCount++;
 $this->curLine = $this->innerCount;
 $this->innerBof = false;
 $this->innerEof = true;
 unset($this->curArray);
 $this->curArray = &$newRec;
 $this->isModify = true;
  }
 

 //保存修改
 function saveModify(){
  if($this->isModify){
   $this->innerRecorders[$this->curLine]= implode($this->sprt2,$this->curArray);
   $this->isModify = false;
   $this->fileModify= true;
  }
 }

 //当指针发生变化时，初始化当前记录数组
 function initRec(){
  $this->curArray = explode($this->sprt2,$this->innerRecorders[$this->curLine]);
  if (count($this->curArray)!=$this->innerFieldsCount){
   echo "The Current Recorder fields count unequal to Table's.n File will close.";
   $this->close();
   return false;
  }
  return true;
 }

 //输出当前记录信息，设计为调试用
 function ddisplay(){
  if ($this->innerCount==0) return false;
  foreach($this->innerFields as $v) echo $v."----";
  echo "
";
  foreach($this->curArray as $v) echo $v."---";
 }

 //检查记录是否已被删除
 function chkDel($key){
  if (empty($key)&&$key!=0){
   echo "the key not appoint.";
   return false;
  }
  if (!isset($this->stringDel)){
   return false;
  }
  if (ereg("(^|,)".$key."(,|$)",$this->stringDel)){
   return true;
  }
  return false;
 }

 //检查提交的字段名是否合法.
 function chkField($field){
  if (empty($field)&&($field!=0)){
   echo "the field not appoint.";
   return -1;
  }
  $vartype = gettype($field);
  switch ($vartype) {
   case "integer":
    if ($field>=$this->innerFieldsCount){
        echo "the field is large than fieldscount";
        return -1;
    }elseif($field<0){
     echo "the field is less than 0";
     return -1;
    }
    return $field;
  case "string":
   foreach ($this->innerFields as $k=>$v) if ($field==$v) return $k;
   echo "the field name not found.";
   return -1;
  default:
   echo "the field is invalid.";
   return -1;
  }
 }

}

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