In PHP, similar_text() and levenshtein() functions are mainly used to compare string similarity; 1. Similar_text() returns a similar percentage or matched number of characters, suitable for fuzzy search and repeated content detection; 2. levenshtein() returns an editing distance, suitable for automatic error correction and input correction; 3. The selection basis is the requirement: if the percentage is required, select similar_text(), and if the number of steps is required, use levenshtein().

Comparing the similarity between two strings is actually quite common in PHP, such as it is used when doing fuzzy searches, spelling checks, or data cleaning. PHP provides two more practical functions: similar_text() and levenshtein() , which can help us determine how close the two strings are.

Let me briefly talk about the difference:

• similar_text() returns a percentage of two strings similar (can also return the number of matching characters)
• levenshtein() returns the edit distance, which is how many operations (add, delete, replace) are required to make the two strings the same

Let’s see how to use it.

How to use similar_text() to determine string similarity

This function is relatively simple and direct, suitable for beginners or scenarios that only require roughly judging the similarity.

Basic usage:

 similar_text("apple", "appel", $percent);
echo $percent; // Output a value similar to 80 or 80.0

Some points to note:

• The third parameter is to refer to the value, so the first step is to add &
• The default return is the number of matching characters. If the $percent parameter is passed, the percentage will be filled.
• The percentage calculation method is (匹配字符數(shù)* 200) / (字符串1長(zhǎng)度字符串2長(zhǎng)度) , so it is not an absolute value, but it can be used to compare

Examples of applicable scenarios:

• The user enters "Beijing". If you want to check "Beijing", you can use this to determine whether it is similar.
• Use as an auxiliary means when detecting duplicate content

How to use levenshtein()? What is suitable for?

If you are more concerned with the "gap" between two strings than the "similarity", then levenshtein() is more appropriate.

Basic examples:

 echo levenshtein("hello", "helo"); // Output 1

It returns the minimum number of modifications. In the example above, "hello" and "helo" are only one letter l apart, so the result is 1.

Some details:

• Supports up to 255 characters, if it exceeds it, it will return -1
• Supports custom insertion, replacement, and deletion costs, such as:

   levenshtein($str1, $str2, 1, 2, 3); // Insert cost 1, replace cost 2, delete cost 3

  Typical application scenarios:

  • Automatic error correction, such as if the user typed the wrong word, the system recommends the closest correct spelling
  • Preprocessing before database query to correct possible input errors

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  Which one is better? How to choose?

  There is no standard answer to this question, it depends on what the problem you are trying to solve:

  • If you want an intuitive "similar percentage", use similar_text() first
  • If you need to know how many steps there is between two strings, use levenshtein()

  For example:

  • When looking for similar names, you may first use levenshtein() to find the result of the minimum editing distance, and then use similar_text() to see if the similarity meets the standard.
  • In terms of performance, both are similar, but if the data volume is large, it is recommended to test which scenario is more suitable for you

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  Basically that's it. Both functions are not complicated, but they are very practical in practical applications. As long as you understand your respective characteristics, it is not difficult to choose.

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