[Calisthenics]

It cannot divide with zero. You can use a temporary variable and set its value to one just for the division.

pawn Код:

new deaths_of_playerid = !DMDEATHS[playerid] ? 1 : DMDEATHS[playerid],
    deaths_of_killerid = !DMDEATHS[killerid] ? 1 : DMDEATHS[killerid];

format(str4, sizeof(str4), "ratio:_%.2f", floatdiv(DMKILLS[killerid], deaths_of_killerid));
format(str5, sizeof(str5), "ratio:_%.2f", floatdiv(DMKILLS[playerid], deaths_of_playerid));