如何使用php替换文本文件中的特定行? [英] how to replace a particular line in a text file using php?
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问题描述
如何使用php替换特定行.我不知道行号.我要替换包含特定单词的行.
how to replace a particular row using php. I dont know the line number. I want to replace a line containing a particular word.
推荐答案
您可以对可放入内存两次的较小文件使用一种方法:
One approach that you can use on smaller files that can fit into your memory twice:
$data = file('myfile'); // reads an array of lines
function replace_a_line($data) {
if (stristr($data, 'certain word')) {
return "replaement line!\n";
}
return $data;
}
$data = array_map('replace_a_line',$data);
file_put_contents('myfile', implode('', $data));
一个简短的说明,PHP> 5.3.0支持lambda函数,因此您可以删除命名的函数声明并将映射缩短为:
A quick note, PHP > 5.3.0 supports lambda functions so you can remove the named function declaration and shorten the map to:
$data = array_map(function($data) {
return stristr($data,'certain word') ? "replacement line\n" : $data;
}, $data);
从理论上讲,您可以使它成为单个(很难遵循)的php语句:
You could theoretically make this a single (harder to follow) php statement:
file_put_contents('myfile', implode('',
array_map(function($data) {
return stristr($data,'certain word') ? "replacement line\n" : $data;
}, file('myfile'))
));
您应该对较大的文件使用另一种(较少占用内存的)方法:
Another (less memory intensive) approach that you should use for larger files:
$reading = fopen('myfile', 'r');
$writing = fopen('myfile.tmp', 'w');
$replaced = false;
while (!feof($reading)) {
$line = fgets($reading);
if (stristr($line,'certain word')) {
$line = "replacement line!\n";
$replaced = true;
}
fputs($writing, $line);
}
fclose($reading); fclose($writing);
// might as well not overwrite the file if we didn't replace anything
if ($replaced)
{
rename('myfile.tmp', 'myfile');
} else {
unlink('myfile.tmp');
}
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