Replace php with a regular expression, and replace php_PHP with a regular expression. tutorial

Use a regular expression to replace the content with php, and use a regular expression to replace php. Use a regular expression to replace the content in php. use a regular expression to replace php with a previous project, that is, there is a Q & A page, such as inserting an expression in the answer or question content. Replace php with regular expressions, and replace php with regular expressions.

A previous project involves a Q & A page, for example, inserting an expression in the answer or question content. The name of the emoticon image (without a suffix, for example, f_002.png) is written in the content and placed in the project, I need to replace the emoticon name with the image when removing the content.

The content stored in the database is as follows: I don't know [f_013] (the last [f_013] is the form of the emoticon stored in the database)

What I need to do is retrieve the content from the database and process the character [f_013] like this in the content into an image address. it is clear that a regular expression is needed here.

1. first, I need to find this string

$rule = "/(?:\[)(f_.[0-9]{1,3})(?:\])/i";

This regular expression matching can help me find the expression string

2. replace the string with the address of the emoticon Image. here, a function is used to replace the regular expression.

This is the function: preg_match_all

echo preg_replace("/(?:\[)(f_.[0-9]{1,3})(?:\])/i","",$line['content']);

$ Line ['content'] this is the content I extracted from the database,

"" This is the image address I want to replace. for example, my image address is like this.
There is a very important knowledge point: "\ $ {1}" it is the character string that stores the expressions in the database.
\ $ {1} = f_013

Here is a complete code I replaced:

  $ Result = array (); $ n = preg_match_all ("/(? : \ [) (F _. [0-9] {1, 3 })(? : \])/I ", $ line ['content'], $ result ); /* returns the number of matching strings */if ($ n = 0 | $ n = false) /* if it is 0 or false, it indicates no expression */
{Echo $ line ['content'];} else
{Echo preg_replace ("/(? : \ [) (F _. [0-9] {1, 3 })(? : \])/I "," ", $ line ['content']) ;}?>

When using php, the regular expression replaces php with a previous project, that is, there is a Q & A page, such as inserting an expression in the answer or question content. Write...