[Nero_3D]

Your functions checks if there are small letters but you never convert them

pawn Код:

CMD:factioncolor(playerid, params[]) {
    new
        color = HexToInt(params)
    ;
    if(color == 0) {
        return SendClientMessage(playerid, -1, "USAGE: /factioncolor [RRGGBB] (0-9, A-F, a-f)");
    }
    color = color << 8 | 0xFF;
    FactionInfo[FACTION_ID][FactionColor] = color;
    return SendClientMessage(playerid, color, "This is the new color of your faction.");;
}

pawn Код:

stock HexToInt(string[]) {
    new
        i,
        result,
        tmp = string[0]
    ;
    do {
        result <<= 4;

        if('0' <= tmp <= '9') {
            result += tmp - '0';
            continue;
        }
        if('A' <= tmp <= 'F') {
            result += tmp - ('A' - 10);
            continue;
        }
        if('a' <= tmp <= 'f') {
            result += tmp - ('a' - 10);
            continue;
        }
        return false;
    } while((tmp = string[++i]));

    return result;
}