[blanic]

I want to forbid this character in the chat, I'm using this code that's not working; can someone help me?
Where do I have to put it to make it working?

PHP код:

stock strreplace(string[], find, replace)
{
    for(new i=0; string[i]; i++)
    {
        if(string[i] == find)
        {
            string[i] = replace;
        }
    }
}
stock GetName(playerid)
{
    new name[24];
    GetPlayerName(playerid, name, sizeof(name));
    strmid(str,name,0,strlen(name),24);
    for(new i = 0; i < MAX_PLAYER_NAME; i++)
    {
        if (str[i] == '_') str[i] = ' ';
    }
    return str;
}