How to deal with the specific usage of the third strpos () parameter

The third parameter of strpos () is currently used for string truncation. to make the code look simpler, someone prompts me to look at the third parameter of strpos, the document shows that the example only contains the first and second parameters. Which of the following is a simple example of using three parameters in the handwriting field. Thank you !!, Are there any official manuals? Usage of the third parameter of http://www.php.net/manual/zh/fun strpos ()
Currently, we are doing string truncation. to simplify the code, someone prompts me to look at the third parameter of strpos. in this document, we can see that the example only contains the first parameter and the second parameter. Which of the following is a simple example of using three parameters in the handwriting field. Thank you !!

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Are there any official manuals? Http://www.php.net/manual/zh/function.strpos.php
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The third parameter is offset. the default value is 0.
If specified, the search starts from the position of the string.