How to Convert a Backslash-Delimited String to an Associative Array in PHP?

Transforming a Backslash-Delimited String into an Associative Array

Converting a string with key-value pairs separated by backslashes into an associative array is a frequent task in PHP programming. Here are some approaches:

Using preg_match_all and array_combine:

The most efficient option is to utilize the preg_match_all function with a regular expression to extract the keys and values. Subsequently, the array_combine function can be used to create an associative array:

preg_match_all("/([^\\]+)\\([^\\]+)/", $string, $p);
$array = array_combine($p[1], $p[2]);

Adapting to Different Delimiters:

The same approach can be generalized to cater to varying key-value and pair delimiters. For example, the following regex can handle colons and commas as separators:

preg_match_all("/ ([^:]+) : ([^,]+) /x", $string, $p);
$array = array_combine($p[1], $p[2]);

Allowing Flexible Delimiters:

Allowing arbitrary delimiters provides greater versatility. The following regex permits keys and values to be separated by different characters:

preg_match_all("/ ([^:=]+) [:=]+ ([^,+&]+) /x", $string, $p);

Constraining Alphanumeric Keys:

To restrict keys to alphanumeric characters, the following regex can be employed:

preg_match_all("/ (\w+) = ([^,]+) /x", $string, $p);

Stripping Spaces and Quoting:

To eliminate whitespace and optional quotes from keys and values, this regex can be used:

preg_match_all("/ \s*([^=]+) \s*=\s* ([^,]+) (?<!\s) /x", $string, $p);

Extracting INI-Style Configurations:

For extracting INI-style configurations, the following regex is useful:

preg_match_all("/^ \s*(\w+) \s*=\s* ['\"]?(.+?)['\"]? \s* $/xm", $string, $p);

Alternative: parse_str

For strings already formatted as "key=value&key2=value2," the parse_str function can be utilized. Combining it with strtr enables the processing of alternative delimiters:

parse_str(strtr($string, ":,", "=&"), $pairs);

Other Approaches:

While less efficient, it is possible to manually explode the string and loop through the array to create the associative array. However, profiling often reveals this method to be slower than the regular expression approach.

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