473,399 Members | 2,146 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,399 software developers and data experts.

Pointer and integer expressions

I have a review test question and was wondering why the answers are the way they are. Could someone please explain what you can and cannot do with the following?

Which of the following expressions are allowed, given that i and j are pointers to the same type and n is an integer?
n = i / j

n = j - i correct?

n = i % j

n = i + j

n += j

j += n correct?

i = j + n correct?

*j correct?

The correct? is what the machine gave me credit for. Why can you do n=j-i and not n=i+j?
Jan 5 '10 #1
1 1452
Banfa
9,065 Expert Mod 8TB
You need to look up pointer arithmetic in your reference material.

However consider the semantic meanings of the expressions given that i and j are memory locations, forget for now that a memory location on many platforms is just an integer offset into memory that is an implementation detail.

For instance

n = i - j

this has the semantic meaning of set n to the difference between memory location i and memory location j that is how many memory locations do I have to move to get from i to j.

Now ask yourself what would be the semantic meaning of

n = i + j

n = i / j

Can you think of a sensible one?
Jan 5 '10 #2

Sign in to post your reply or Sign up for a free account.

Similar topics

21
by: MOvetsky | last post by:
Is the following code ISO C++ standard compliant? If yes, is it guaranteed that it will not crash on compliant platforms? If yes, will it print "Pointers are equal" on any compliant platform? Will...
40
by: Foobarius Frobinium | last post by:
Please review this guide for clarity, accuracy, etc. so I can hopefully compile a very good tutorial on how to use pointers in C, including advanced topics, that is easy to follow and exposes the...
204
by: Alexei A. Frounze | last post by:
Hi all, I have a question regarding the gcc behavior (gcc version 3.3.4). On the following test program it emits a warning: #include <stdio.h> int aInt2 = {0,1,2,4,9,16}; int aInt3 =...
10
by: houstorx | last post by:
I've been looking at the committee draft of the C99 specification, specifically the one at this URI: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n843.pdf. I don't have a copy of the official...
42
by: xdevel | last post by:
Hi, if I have: int a=100, b = 200, c = 300; int *a = {&a, &b, &c}; than say that: int **b is equal to int *a is correct????
11
by: quakewang | last post by:
hi, I have define in a head file like this: #define GLUT_BITMAP_9_BY_15 ((void*)2) #define GLUT_BITMAP_8_BY_13 ((void*)3) #define GLUT_BITMAP_TIMES_ROMAN_10 ...
156
by: Lame Duck | last post by:
Hi Group! I have a vector<floatvariable that I need to pass to a function, but the function takes a float * arguement. That's OK, I can convert by doing &MyVector.front(), but when I get back a...
17
by: matevzb | last post by:
I've ran into some fishy code that, at first glance, is buggy, but it seems to work correctly and none of the compilers I've tried (five so far, on various systems) gives any warnings. The code:...
19
by: =?iso-8859-1?b?VG9t4XMg0yBoyWlsaWRoZQ==?= | last post by:
Coming originally from C++, I used to do the likes of the following, using a pointer in a conditional: void Func(int *p) { if (p) { *p++ = 7; *p++ = 8;
41
by: simonl | last post by:
Hi, I've been given the job of sorting out a crash in our product for which we have the crash information and an avi of the event (which can't possibly match but more of that later...) (btw this...
0
by: Charles Arthur | last post by:
How do i turn on java script on a villaon, callus and itel keypad mobile phone
0
BarryA
by: BarryA | last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
1
by: nemocccc | last post by:
hello, everyone, I want to develop a software for my android phone for daily needs, any suggestions?
1
by: Sonnysonu | last post by:
This is the data of csv file 1 2 3 1 2 3 1 2 3 1 2 3 2 3 2 3 3 the lengths should be different i have to store the data by column-wise with in the specific length. suppose the i have to...
0
by: Hystou | last post by:
There are some requirements for setting up RAID: 1. The motherboard and BIOS support RAID configuration. 2. The motherboard has 2 or more available SATA protocol SSD/HDD slots (including MSATA, M.2...
0
marktang
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,...
0
by: Hystou | last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can...
0
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...
0
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.