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Groups > comp.lang.c > #164087

Re: Can this program be improved?

From Lew Pitcher <lew.pitcher@digitalfreehold.ca>
Newsgroups comp.lang.c
Subject Re: Can this program be improved?
Date 2021-12-26 19:22 +0000
Organization A noiseless patient Spider
Message-ID <sqafdf$qtd$1@dont-email.me> (permalink)
References <sq63mi$gom$1@dont-email.me> <sq6b3t$ce5$1@dont-email.me> <sqae28$g83$1@dont-email.me>

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On Sun, 26 Dec 2021 18:52:14 +0000, Manu Raju wrote:

> On 25/12/2021 05:44, Andrey Tarasevich wrote:
>> On 12/24/2021 5:00 PM, Manu Raju wrote:
>>>>
>>>> #include <stdio.h>
>>>> #include <stdlib.h>
>>>> #include <math.h>
>>>>
>>>> int main()
>>>> {
>>>>    float P = 100000; // Loan Amount
>>>>    float r = 7.5; // Advertised Interest Rate
>>>>    int n = 12; // Loan Period
>>>>    float payBack = (P * r / 1200 * pow(1 + r / 1200, n)) / (pow((1 +
>>>> r / 1200), n) - 1);
>>>>    float Opening = P; // Opening Balance
>>>>    float closing = 0;  // Closing Balance
>>>>    float interest = 0;
>>>>    float Total = 0;
>>>>    float repaid = 0;
>>>>
>>>>    printf("\nMonthly payment is: %.2f\n", payBack);
>>>>
>>>>      printf("%10s %14s %13s %10s %14s %12s\n", "Month", "Beginning",
>>>> "Interest", "Total", "Repayment", "Balance");
>>>>
>>>>      for (int i = 1; i <= n; i++)
>>>>      {
>>>>          for (int j = 0; j <= n; j++)
>>>>          {
>>>>              interest = Opening * r / 1200;
>>>>              Total = Opening + interest;
>>>>              repaid = payBack;
>>>>              closing = Total - payBack;
>>>>          }
>>>>          printf("%10d %14.0f %13.0f %10.0f %14.0f %12.0f\n", i,
>>>> Opening, interest, Total, repaid, closing);
>>>>          Opening = closing;
>>>>      }
>>>>      return 0;
>>>> }
>>
>>
>> 9. "Magical constants"? What on Earth is `1200`?
> 
> 
> It is just a figure 12 * 100. You first need to convert percentage into 
> decimals by dividing by 100; Then you need to divide the number again by 
> 12 to give monthly rate. Interest rate is normally annual rate. Hope 
> this explains the magic number.

Well, you've explained it to us, but not to whomever will read your program next.

A good part of the art of programming is writing readable code; readable to you,
readable to you in 5 years from now, readable to the programmer that has to make
the next change to it, readable to the programmer who has to fix the bug in it.

Your use of 1200 is confusing, unless you already know that it facilitates the
conversion of a yearly interest rate expressed as a percent into a monthly
interest rate expressed as a decimal. It is worth noting that, should you
change the loan period expressed in P, you would /also/ have to change this
1200 "magic number" appropriately (or is P a "loan period in years"? if so,
then I believe that your interest calculations are wrong.)


-- 
Lew Pitcher
"In Skills, We Trust"

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Thread

Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-25 01:00 +0000
  Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-24 21:44 -0800
    Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2021-12-25 12:56 +0100
    Re: Can this program be improved? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-12-25 11:13 -0800
    Re: Can this program be improved? Manfred <noname@add.invalid> - 2021-12-25 23:50 +0100
    Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 18:52 +0000
      Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-26 19:22 +0000
        Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 21:30 +0000
          Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-26 22:02 +0000
          Re: Can this program be improved? Richard Damon <Richard@Damon-Family.org> - 2021-12-26 18:24 -0500
          Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-27 00:47 +0000
    Re: Can this program be improved? Guillaume <message@bottle.org> - 2021-12-29 17:52 +0100
      Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-29 17:49 +0000
        Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-29 11:33 -0800
          Re: Can this program be improved? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-12-29 22:45 -0500
            Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-30 00:35 -0800
              Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2021-12-30 10:19 +0100
          Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 18:19 +0000
            Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 19:33 +0000
        Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 14:37 -0800
          Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-29 23:09 +0000
            Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2021-12-29 23:54 +0000
              Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 16:11 -0800
              Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 00:34 +0000
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-30 12:49 +0000
                Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 21:04 +0000
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-31 02:13 +0000
            Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 16:09 -0800
              Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 00:59 +0000
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 17:48 -0800
                Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 20:47 +0000
              Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-30 01:06 +0000
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-12-30 04:48 -0800
                Re: Can this program be improved? Manfred <noname@add.invalid> - 2021-12-30 18:16 +0100
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-31 02:20 +0000
                Re: Can this program be improved? Manfred <noname@add.invalid> - 2021-12-31 18:25 +0100
                Re: Can this program be improved? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-12-31 18:13 -0500
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-31 23:59 +0000
                Re: Can this program be improved? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-12-31 16:20 -0800
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-31 16:35 -0800
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 00:53 +0000
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-31 20:22 -0800
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-12-31 22:04 -0800
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-01 14:59 -0800
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-02 17:22 -0800
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-02 20:49 -0800
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 03:09 -0800
                Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-03 16:22 +0000
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-03 14:42 -0800
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 14:52 -0800
                Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-03 22:58 +0000
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 04:27 -0800
                Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-04 13:39 +0000
                Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 00:18 +0100
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-03 15:24 -0800
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 15:43 -0800
                Re: Can this program be improved? Öö Tiib <ootiib@hot.ee> - 2022-01-03 21:19 -0800
                Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-04 09:23 +0100
                Re: Can this program be improved? Guillaume <message@bottle.org> - 2022-01-04 18:18 +0100
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 10:35 -0800
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-04 14:07 -0800
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 15:11 -0800
                Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-04 15:47 -0800
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 18:30 -0800
                Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-04 23:46 +0000
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-04 18:41 +0000
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 10:52 -0800
                Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-04 19:00 +0000
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 11:15 -0800
                Re: Can this program be improved? Guillaume <message@bottle.org> - 2022-01-04 21:57 +0100
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-04 21:02 +0000
                Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-04 21:38 +0000
                Re: Can this program be improved? Manfred <noname@add.invalid> - 2022-01-04 23:01 +0100
                Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 09:31 +0100
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 01:30 -0800
                Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 14:55 +0100
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 06:21 -0800
                Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 16:49 +0100
                Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-04 15:56 +0000
                Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-04 15:03 +0000
                Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-03 22:54 +0000
                Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-03 09:22 +0100
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 03:30 -0800
                Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-03 17:22 +0100
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 08:48 -0800
                Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-03 18:42 +0100
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-03 17:59 +0000
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 11:09 -0800
                Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-03 20:32 +0100
                Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 11:58 -0800
                Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-03 18:13 +0000
                Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-03 20:05 +0000
                Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 16:53 +0000
          Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 00:29 +0000
  Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-25 12:47 +0000
    Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 18:56 +0000
  Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-25 17:38 +0000
    Re: Can this program be improved? Öö Tiib <ootiib@hot.ee> - 2021-12-25 10:58 -0800
      Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-25 19:16 +0000
        Re: Can this program be improved? Öö Tiib <ootiib@hot.ee> - 2021-12-25 11:25 -0800
      Re: Can this program be improved? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-12-25 15:01 -0800
        Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-25 23:09 +0000
          Re: Can this program be improved? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-12-25 20:56 -0800
    Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2021-12-25 19:30 +0000
      Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-25 15:50 -0800
        Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 19:02 +0000
    Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-25 11:53 -0800
    Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 19:00 +0000
  Re: Can this program be improved? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-12-25 11:22 -0800
    Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 19:01 +0000
  Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-12-25 13:27 -0800
    Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-25 16:06 -0800
  Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-29 15:21 +0000

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