SplFileObject + LimitIterator + 偏移量

问题描述

我有两行数据文件(两行只是为了我的例子，实际上，该文件可以包含数百万行)，我使用带有偏移量的 SplFileObject 和 LimitIterator.但是这种组合在某些情况下会产生奇怪的行为:

I have data file with two lines (two lines just for my example, in real, that file can contain millions of lines) and I use SplFileObject and LimitIterator with offseting. But this combination have strange behaviour in some cases:

$offset = 0;
$file = new \SplFileObject($filePath);
$fileIterator = new \LimitIterator($file, $offset, 100);
foreach ($fileIterator as $key => $line) {
  echo $key;
}

输出为:01

但是当 $offset 设置为 1 时，输出为空白(foreach 不迭代任何行).

But with $offset set to 1, output is blank (foreach doesn't iterate any line).

我的数据文件包含:

{"generatedAt":1434665322,"numRecords":"1}
{"id":"215255","code":"NB000110"}

我做错了什么?

谢谢

推荐答案

必需:

使用 SplFileObject 处理来自以下位置的多个记录:

Use SplFileObject to process a number of records from:

• 给定的起始记录编号
• 对于给定数量的记录或直到 EOF.

问题是 SplFileObject 对文件中的 last record 感到困惑.这会阻止它在 foreach 循环中正常工作.

The issue is that SplFileObject gets confused as regards the last record in the file. This prevents it working correctly in foreach loops.

此代码使用 SplFileObject 和跳过记录"和处理记录".唉，它不能使用 foreach 循环.

This code uses the SplFileObject and 'skip records' and 'processes records'. Alas, It cannot use foreach loops.

• 从文件开头跳过一些记录 ($offset).
• 处理给定数量的记录或以文件结尾为单位 ($recordsToProccess)

代码:

<?php

$filePath = __DIR__ . '/Q30932555.txt';
// $filePath = __DIR__ . '/Q30932555_1.txt';

$offset = 1;
$recordsToProcess = 100;

$file = new \SplFileObject($filePath);

// skip the records
$file->seek($offset);

$recordsProcessed = 0;
while (     ($file->valid() || strlen($file->current()) > 0)
         &&  $recordsProcessed < $recordsToProcess
       ) {
    $recordsProcessed++;
    echo '<br />', 'current: ', $file->key(), ' ', $file->current();
    $file->next();
}

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