php的文件读取和写入似乎对未知格式的文件不管用

<?php$file="宋1.mp3.part1";$file1="宋2.mp3.part1";$file2="宋3.mp3.part1";$fp = fopen($file, "a");$fp1 = fopen($file1, "r");$fp2 = fopen($file2, "r");// if(!$fp1) echo "aa";// return;//fseek(fp, 0, SEEK_END);$index=0; while(!feof($fp1)){//测试文件指针是否到了文件结束的位置         $content=fread($fp1,10);         if(fwrite($fp,$content)==false)		echo "不能写入到文件 $filename"; 		$index++;		echo $index;    } 	$index=0;	while(!feof($fp2)){//测试文件指针是否到了文件结束的位置         $content=fread($fp2,10);         fwrite($fp,$content); 			$index++;		echo $index;    }     fclose($fp);      fclose($fp1);     fclose($fp2); 	rename ($file, "a.mp3"); 	echo "ok";?>

$str="宋1.txt";$str=iconv("utf-8", "GBK", $str);//注释掉就会失败$fp = fopen($str, "a");if(fwrite($fp,"losasds")!==false) echo "ok";else echo "fail";fclose($fp);

$str="宋1.txt";$str=iconv("utf-8", "GBK", $str);//注释掉就会失败$fp = fopen($str, "a");if(fwrite($fp,"losasds")!==false) echo "ok";else echo "fail";fclose($fp);