Detailed example of how to delete specified lines in txt files in PHP

PHP is a commonly used programming language that is widely used in web development. This article mainly describes how to use PHP to delete specified lines in txt files.

1. Read the file content
First, we need to read the content of the txt file. The entire file can be read into a string using the file_get_contents() function in PHP.

For example, we have a test.txt file, and you can use the following code to read the content:

$file = 'test.txt';
$content = file_get_contents($file);

2. Split the file content into an array
Next, we will Split by rows and put each row into an array. This can be achieved using the explode() function in PHP.

The specific code is as follows:

$file = 'test.txt';
$content = file_get_contents($file);

// 将内容按行分割，并将每一行放入一个数组中
$lines = explode(PHP_EOL, $content);

Among them, PHP_EOL is the newline character constant in PHP, which means that the newline characters in different operating systems may be different. Using constants can ensure the compatibility of the code.

3. Delete the specified row
Next, we need to delete the specified row. Suppose we want to delete the 3rd line, we can use the following code:

unset($lines[2]);

Among them, the unset() function is used to delete the specified variable, here it is used to delete the 3rd element in the array $lines. It should be noted that array subscripts start from 0, so row 3 has subscript 2 in the array.

4. Merge the content into a string and write it to the file
Finally, we need to re-merge the modified content into a string and write it to the original file. This can be achieved using the file_put_contents() function in PHP.

The specific code is as follows:

$file = 'test.txt';
$content = file_get_contents($file);

// 将内容按行分割，并将每一行放入一个数组中
$lines = explode(PHP_EOL, $content);

// 删除指定的行
unset($lines[2]);

// 将内容合并为字符串
$new_content = implode(PHP_EOL, $lines);

// 将修改后的内容写回文件
file_put_contents($file, $new_content);

To sum up, the above is the entire process of using PHP to delete specified lines in a txt file.

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