Insert keywords to the string at random position in PHP

Keyword $ times = 4 is inserted into the string at a random position in PHP. // keyword frequency $ keyword = "[fuck ]"; // The keyword to be replaced $ str = "Brown is the right Chinese and Western Medicine Group of the aluminum sulfate group. The las will be displayed in the third part of the Chinese and Western medicine. iasfls. sdmflaskdf L. A. Law is stuck. oh, iuoi020990. open time. PHP random position. Insert a keyword to the string.

$ Times = 4; // keyword frequency
$ Keyword = "[fuck]"; // keyword to be replaced
$ Str = "Brown is staying in the aluminum sulfate group, right in the Chinese and Western Medicine 3. the las region is determined. iasfls. sdmflaskdf law in LA is stuck. oh, iuoi020990, it's crazy ";
$ Strlen = mb_strlen ($ str, "gb2312 ");
// Randomly generate the insert location, and determine the insert frequency based on $ times
For ($ I = 0; $ I <$ times; $ I ++)
{
$ Arr [] = mt_rand (0, $ strlen );
}
$ Arr = array_unique ($ arr); // filter repeated array elements
Sort ($ arr); // sorts the array again, from small to large by value
// Start replacement
$ I = 0;
$ Str_new = "";
Foreach ($ arr as $ v)
{
$ Str_new. = mb_substr ($ str, $ I, $ v-$ I, "gb2312"). $ keyword;
$ I = $ v;
}
$ Str_new. = mb_substr ($ str, $ I, $ strlen-$ I, "gb2312 ");
Echo ($ str_new );