public OnPlayerText(playerid, text[]) //This is called every time a player tries to type something, other than a command, such as when talking to other players
{
    if(IsPlayerAdmin(playerid)) //If they are an admin, you can replace this with your own admin variable
    {
        new string[150], name[MAX_PLAYER_NAME];
        GetPlayerName(playerid, name, MAX_PLAYER_NAME);
        format(string,sizeof(string),"[ADMIN] %s: %s", name, text); //Editing the format and adding admin tag in front of name
        SendClientMessageToAll(0xFFFF00FF, string); //Sends message to all
        return 0; //Return false for sending custom chat, so it doesn't send your message twice
    }
    return 1; //Otherwise return 1 and send the message as normal
}

C:\Users\Hunor\Desktop\tag.pwn(1) : warning 235: public function lacks forward declaration (symbol "OnPlayerText")
C:\Users\Hunor\Desktop\tag.pwn(3) : error 017: undefined symbol "IsPlayerAdmin"
C:\Users\Hunor\Desktop\tag.pwn(5) : error 017: undefined symbol "MAX_PLAYER_NAME"
C:\Users\Hunor\Desktop\tag.pwn(5) : error 009: invalid array size (negative, zero or out of bounds)
C:\Users\Hunor\Desktop\tag.pwn(5) : error 036: empty statement
C:\Users\Hunor\Desktop\tag.pwn(5) : fatal error 107: too many error messages on one line

Compilation aborted.Pawn compiler 3.2.3664	 	 	Copyright © 1997-2006, ITB CompuPhase


5 Errors.

#include <a_samp>