Php adds a keyword connection to the article. how does one control the number of links automatically added to the article content? What should I do?

Php adds a keyword connection to the article. how does one control the number of links automatically added to the article content? I have now implemented the php output of the specified html keyword link to the specified URL, but one problem is that all the keywords in this article will be linked, I want to control the number of times it links or just let it link the first keyword in the article. how can I implement php to add a keyword connection to the article, how does one control the number of links to automatically add links to the article content?
I have now implemented the php output of the specified html keyword link to the specified URL, but one problem is that all the keywords in this article will be linked, I want to control the number of times it links, or just let it link the first keyword in the article. how can I implement this? The code for automatically linking implemented keywords is as follows:
Function keylink ($ cont ){
$ Keys = array (
Array ('keyword 1', 'http: // link 1 ')
);
Foreach ($ keys as $ nkeys ){
$ Cont = preg_replace ("/($ nkeys [0])/iU", "$ nkeys [0]", $ cont );
}
Return $ cont;
}
Php !!!

------ Solution --------------------
Mixed preg_replace (mixed $ pattern, mixed $ replacement, mixed $ subject [, int $ limit =-1 [, int & $ count])

The fourth parameter, with a limit of 1.