PHP函数编辑配置文件

I'm looking for a PHP function that I can use to edit key/value pairs in a text file.

What I want to do (PHP):

changeValue(key, bar);

and have in setings.txt:

key = foo
key2 =foo2

Change to:

key = bar
key2 = foo2

What I got so far (not working):

function changeValue($input) {
    $file = file_get_contents('/path/to/settings.txt');
    preg_match('/\b$input[0]\b/', $file, $matches);
    $file = str_replace($matches[1], $input, $file);
    file_put_contents('/path/to/settings.txt', $file);
}

How to update an ini file with php? got me started. I read many other questions but I couldn't get it working.

I would use JSON with at least the JSON_PRETTY_PRINT option to write and json_decode() to read.

// read file into an array of key => foo
$settings = json_decode(file_get_contents('/path/to/settings.txt'), true);

// write array to file as JSON
file_put_contents('/path/to/settings.txt', json_encode($settings, JSON_PRETTY_PRINT));

Which will create a file such as:

{
    "key": "foo",
    "key2": "bar",
    "key3": 1
}

Another possibility is var_export() using a similar approach, or another simple example for what you're asking:

// read file into an array of key => foo
$string = implode('&', file('/path/to/settings.txt', FILE_IGNORE_NEW_LINES));
parse_str($string, $settings);

// write array to file as key=foo
$data = implode("
", $settings);
file_put_contents('/path/to/settings.txt', $data);

So read in the file, change the setting $setting['key'] = 'bar'; and then write it out.

Instead of using file_get_contents use file, this reads each line in as an array. Under you see working code. Had a little problem with write array added more breaks but not sure why.

changeValue("key", "test123"); 

function changeValue($key, $value) 
{
    //get each line as an array. 
    $file = file("test.txt"); 

    //go through the array, the value is references so when it is changed the value in the array is changed. 
    foreach($file as &$val) 
    { 
        //check if the string line contains the current key. If it contains the key replace the value. substr takes everything before "=" so not to run if the value is the same as the key. 
       if(strpos(substr($val, 0, strpos($val, "=")), $key) !== false)
        {
           //clear the string
           $val = substr($val, 0, strpos($val, "="));
           //add the value 
           $val .= "= " . $value; 
        }
    }
    //send the changed array writeArray(); 
    writeArray($file); 
 }

function writeArray($array) 
{
    $str = ""; 
    foreach($array as $value)
    {
        $str .= $value . "
"; 
    }

    //write the array. 
    file_put_contents('test.txt', $str);
}

?>