strtr vs str_replace: When to Use Which for String Replacements?

When to Use strtr vs str_replace

The PHP functions strtr and str_replace both perform string replacements, but key differences exist in their behavior.

Key Differences:

• Key Sorting: strtr sorts its search strings by length in descending order, while str_replace processes keys in the order they are defined.
• Replacement Order: strtr replaces the largest matching string first, while str_replace replaces keys sequentially.

Example:

Consider the following code:

<code class="php">$text = "PHP: Hypertext Preprocessor";
$arr = array("PHP" => "PHP: Hypertext Preprocessor", "PHP: Hypertext Preprocessor" => "PHP");

$text_strtr = strtr($text, $arr);
$text_str_replace = str_replace(array_keys($arr), array_values($arr), $text);</code>

• strtr will sort the keys by length and replace "PHP: Hypertext Preprocessor" with "PHP" first, effectively reverting the text to its original value.
• str_replace will replace "PHP" with "PHP: Hypertext Preprocessor" and then replace "PHP: Hypertext Preprocessor" with "PHP," resulting in a different outcome: "PHP: Hypertext Preprocessor."

When to Use strtr:

• Prefer strtr when the order of replacements is not critical or when replacing the longest matching string is desirable.

When to Use str_replace:

• Use str_replace when the specific order of key replacements is important.

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