我说奇怪了，fwrite函数竟然一次写两条？

for($i=0;$i<count6;$i++){
if(ereg("",$)){
$f_open=fopen(".txt","a");
fwrite($f_open,$);
fclose($f_open);
}else{
$f_open2=fopen("","a");
fwrite($f_open2,$);
fclose($);
}
}
很纳闷的说，大概构思就这样，测试发现竟然写了两条……求解