As an old C programmer, I'm surprised by some results I'm getting with
integer division. For example: -1/1000
-1 -9/2
-5
I expect the results of these expressions to be 0 and -4,
respectively.
I've looked at faqs and documentation, and nothing jumped out at me. Can
anyone explain the reasoning for this?
Thanks,
Michael Cornelius 2 1846
> I've looked at faqs and documentation, and nothing jumped out at me. Can anyone explain the reasoning for this?
According to my math book integer division is defined as such:
a/b = q, where a = b*q + r and r is the remainder.
A remainder (ei a modulo) is always positive, effectively flooring all
the division operations.
Rory Geoghegan wrote: I've looked at faqs and documentation, and nothing jumped out at me. Can anyone explain the reasoning for this?
According to my math book integer division is defined as such: a/b = q, where a = b*q + r and r is the remainder.
A remainder (ei a modulo) is always positive, effectively flooring all the division operations.
Remainders are always positive, but modulo can be
defined as either positive or negative (for negative
arguments). There are pros and cons for doing it either
way, although the Python way seems to have more pros
than cons.
--
Steven D'Aprano This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: Imbaud Pierre |
last post by:
integer division and modulo gives different results in c and python,
when negative numbers
are involved. take gdb as a widely available c interpreter
print -2 /3
0 for c, -1 for python.
more amazing, modulos of negative number give negative values! (in c).
from an algebraic point of view, python seems right, but I thought
python conformity to the underlying c compiler was a strong commitment,
obviously not here, and I found no...
|
by: Teis Draiby |
last post by:
In .NET, can I be sure that the result of a division between two integers
always is truncated rather that rounded to nearest?
Example:
99 / 50 = 1
regards, Teis
|
by: Darius Fatakia |
last post by:
hi,
i'm new to MS Visual Studio and C++ but not to C programming in general. i'm
trying to divide two integers and get their actual quotient (eg 5/3 =
1.666667 etc). i thought i had type cast correctly, but please let me know,
because it appears to be rounding off. my code follows. Thanks!
void DrawLine(GLint x1, GLint y1, GLint x2, GLint y2)
{
int i, pk, dy, dx, yc, xc, inc, temp;
|
by: Janice |
last post by:
I got this question from my textbook and I cannot understand the theory.
When a signed positive integer X divided by pow(2,k), the result is shifting
k bits to right and putting w-k bits of 0 from the most significant bits.
However, when the X is a negative number divided by pow(2,k), the shifting
and sign bit extension method doesnt give the correct answer?
What kind of bias should we make on the X before the division?
Thanx
|
by: Mike S |
last post by:
Does anyone know the logic behind why in VB.NET the result of a
floating-point division ('/') is -rounded- on being converted to an
integer type, such as with statements like
Dim x As Integer = 2/3 'after assignment, x is 1, whereas a sane person
would say it should be 0
Does Microsoft have a reason for this design decision? I understand
that this type of rounding can reduce the overall error in long
computation chains by reducing the...
| |
by: Candace |
last post by:
I am using the following code to pick off each digit of a number, from right
to left. The number I am working with is 84357. So for the first iteration it
should return the number 7 and for the second iteration it should return the
number 5, and so on. But for some reason on the first iteration returns the
expected results. Each subsequent iteration returns the number plus 1. In
order words, when I run the program I am getting: 7, 6, 4, and...
|
by: André |
last post by:
Hello,
I need to know whether the result of a division is a integer or not.
dim x =60
dim y = 3
if x/y is a integer then
....
else
....
|
by: charles.lobo |
last post by:
Hi,
I have recently begun using templates in C++ and have found it to be
quite useful. However, hearing stories of code bloat and assorted
problems I decided to write a couple of small programs to check. What I
expected was that there would be minor code bloat and some speed
improvement when using templates. However...
I wrote a basic list container (using templates), and a list container
(using virtual derived classes). I also tried...
|
by: Default User |
last post by:
Hi,
If I have three 64 bit integers and I want to do this operation on them:
x*y/z
Lets say that what we are multiplying by (y) is offset by what we are
dividing by (z) so that the final answer will fit in a 64-bit integer.
Let me simplify it by using unsigned chars (8 bits):
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look !
Part I. Meaning of...
|
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
| |
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
|
by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
|
by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
|
by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
|
by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
| |
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
| | |