Question

如何从包含10行或更多行的变量中仅获取特定行？我试过这段代码：

tasks:
  - name: Copy bulk files
    copy:
      src: "{{ item }}"
      dest: /ansible/sri
    with_fileglob: "/tmp/guru/{{ copy }}*"

但现在正在工作。

这是我的完整代码：

$line = explode('/n', $lines);

Answer 1

如果您尝试按行分割，则应使用：

$line = explode("\n", $lines);

举个例子：

<?php

$lines = "first line
second line
third line
fourth line";

$line = explode("\n", $lines);

echo $line[3];

这会给你fourth line。请记住，数组中的第一个元素是0，第二个是1，第三个是2，依此类推......

Answer 2

我不确定为什么爆炸对你不起作用（它应该）。我建议PHP_EOL作为分隔符，看看它是如何抓住你的。为了便于比较，您可以使用preg_match()，但这会更慢。

代码：（Demo）

$string='line1
line2
line3 line 3
line4
line five
line 6
line 7
line eight
line 9
line 10
line eleven';

for($x=1; $x<10; $x+=2){  // $x is the targeted line number
    echo "$x preg_match: ";
    echo preg_match('/(?:^.*$\R?){'.($x-1).'}\K.*/m',$string,$out)?$out[0]:'fail';
    echo "\n  explode: ";
    echo explode(PHP_EOL,$string)[$x-1];
    echo "\n---\n";
}

输出

1 preg_match: line1
  explode: line1
---
3 preg_match: line3 line 3
  explode: line3 line 3
---
5 preg_match: line five
  explode: line five
---
7 preg_match: line 7
  explode: line 7
---
9 preg_match: line 9
  explode: line 9
---

我想的越多，您的报价可能会遇到问题。单引号会将\n呈现为两个非空白字符\和n。您必须使用双引号将其视为换行符。

Another demo：

echo 'PHP_EOL  ',explode(PHP_EOL,$string)[0];     // PHP_EOL works
echo "\n\n",'"\\n"  ',explode("\n",$string)[0];  // "\n" works
echo "\n\n","'\\n'  ",explode('\n',$string)[0];  // '\n' doesn't work, the newline character is "literally" interpreted as "backslash n"

输出：

PHP_EOL  line1     // This is correct

"\n"  line1        // This is correct

'\n'  line1        // The whole string is printed because there is no "backslash n" to explode on.
line2
line3 line 3
line4
line five
line 6
line 7
line eight
line 9
line 10
line eleven

从变量中获取特定行

2 个答案: