fopen表示打开流失败:未定义错误:0，但文件存在已通过 - fopen says failed to open stream: Undefined error: 0 but the fileexist is passes

fopen says failed to open stream: Undefined error: 0 but the fileexist is passes

我正在尝试使用以下代码查找WAV文件持续时间。

if ( !file_exists($location_wmv.$name_wmv) ) {
            echo "<BR> File Does not Exist<BR>";
            } else {
                echo "<BR> File Exist<BR>";
             }
        $file = $location_wmv.$name_wmv;
        $fp = fopen($file, ‘r’);
        $size_in_bytes = filesize($file);
        fseek($fp, 20);
        $rawheader = fread($fp, 16);
        $header = unpack(‘vtype/vchannels/Vsamplerate/Vbytespersec/valignment/vbits’,
        $rawheader);
        $sec = ceil($size_in_bytes/$header['bytespersec']);
        $duration_wmv = $sec;
        echo "<BR> Raw Suration.". $duration_wmv . "<BR>";
        $duration_wmv = gmdate("H:i:s", $demo_song_duration_sec);
        echo "<BR>WAV Duration".$duration_wmv;

这里file_exists函数表示文件存在。但是fopen上写的是failed to open stream: Undefined error: 0该文件实际上存在于文件夹中。但是我仍然得到这个错误

This:

$fp = fopen($file, ‘r’);

看起来可疑的。这些是反引号吗?也许尝试:

$fp = fopen($file, 'r');

(简单的引用)