comp.lang.c.moderated Google Group

Re: C Multithreading variable memorization

francis.glassbo...@btinternet.com (Francis Glassborow) — Thu, 25 Apr 2013 22:23:19 UT

Is there an outline?Does it depends on compiler or SO?How is the memory
divided?
Thank you for your replay.

C (in common with most other programming languages) does bot specify how
things are done only what the results shall be. An implementation is
free to provide storage for variables in any way that it sees fit. A

Free "Practical Design Patterns in C" book.

rloginu...@gmail.com — Mon, 11 Mar 2013 23:25:50 UT

[link]
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Re: why I got this answer?

ja...@xnet.co.nz (Jasen Betts) — Mon, 11 Mar 2013 23:25:47 UT

n 'evaporates' after you hit the return
the value returned in p points to where n used to be.

999 got put where n used to be.

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Re: Why sizeof(main) = 1?

schwa...@dqel.com (Barry Schwarz) — Tue, 26 Feb 2013 16:51:20 UT

On Fri, 4 Jan 2013 18:14:52 -0600 (CST), Myth__Buster

sizeof(char) is always 1, not just usually. Why do you think
sizeof(char) being 1 has any effect on sizeof(void*) or sizeof(char*)?

This second argument contains a constraint violation and therefore
requires a diagnostic. (The sizeof operator cannot be applied to an

Re: "warning: assignment from incompatible pointer type [enabled by default]"

jeanpierre.lej...@quoininc.com (LeJacq, Jean Pierre) — Tue, 26 Feb 2013 16:48:02 UT

You are attempting to declare next with a yet undefined type. You must first
make declare the struct.

/* Declaration of struct. */
struct LLNODE;

/* Declaration of typedef. */
typedef struct LLNODE LLNODE;

/* Definition of struct. */
struct LLNODE {
char *name;
struct LLNODE *next;

Call for Papers: ACCU 2013 conference

jrbjag...@googlemail.com — Fri, 14 Sep 2012 17:53:11 UT

ACCU invites you to propose a session for its leading software development conference.
The conference will be held in Bristol, England, from the 9th to the 13th April inclusive.
Our opening keynote speakers will be Eben Upton, Mr Raspberry Pi.

To propose a session please email the following information to confere...@accu.org

distributing data across a structure (new to c please help)

mke...@gmail.com (nwdpil) — Fri, 10 Aug 2012 01:32:00 UT

the ulimate goal is to read the MZ header from a binary windows pe file, which is simple enough. anyway the theory goes (and this is the bit i dont understand im new to c programming) i memcpy the data from the file ACROSS a struct. is this possible? i dont understand how to initialise and manipulate the struct. can i copy a set of data that is 16bytes long, to a struct with two 8byte children and will memcpy then distribute the data for me if i pass it pointers?

Help with C

bruce.mcgove...@gmail.com (Bruce McGoveran) — Wed, 25 Jul 2012 02:39:07 UT

Hi. To understand C better, I am working my way through The C Programming Language (a.k.a K and R). I have some questions about how to implement some of the solutions to the problems presented in the text. I have The C Answer Book, too. My questions also relate to that book's suggested implementations. There are some minor variations between my solutions and the book's, which I would like to understand better.

fgets - design deficiency: no efficient way of finding last character read

jonona...@googlemail.com (John Reye) — Mon, 23 Apr 2012 13:33:45 UT

Hello,

The last character read from fgets(buf, sizeof(buf), inputstream) is:
'\n'
OR
any character x, when no '\n' was encountered in sizeof(buf)-1
consecutive chars, or when x is the last char of the inputstream

***How can one EFFICIENTLY determine if the last character is '\n'??
"Efficiently" means: don't use strlen!!!

which one is faster?

fat...@gmail.com (echo ma) — Wed, 04 Apr 2012 23:05:42 UT

on a 32bit system.

struct TestStruct
{
unsigned short a;
unsigned short b;
unsigned int c;
struct TestStruct t;
t.a = 0; //step 1
t.b = 1; //step 2
t.c = 2; //step 3

Questing is : Are these 3 steps having the same perfomance time?

Sorry for my poor english.

Pointers and Memory-Mapped Files

heat...@mason.com (Heather Mason) — Mon, 19 Mar 2012 18:40:47 UT

Hey everyone,

I'm attempting to work with a large file which multiple processes may
read from and write to. I plan to use memory mapping to point to
specific portions of the file I would like to modify. My question is how
to properly handle an instance in which the file expands from the front,

Rounding of doubles

poenik...@fastmail.co.uk (Sian Mountbatten) — Mon, 19 Mar 2012 18:40:02 UT

Has anybody used the functions such as fegetround and fesetround. What
do these functions return?

I'm trying to find a function which will round a double to
(1) the nearest integer, with 0.5 rounded to 0.0 and 1.5 to 2.0
(2) the nearest integer near zero, with 1.5 rounded to 1.0 and -1.5 to -1.0

I/O in C99

seima...@gmail.com (Seima) — Mon, 19 Mar 2012 18:41:16 UT

Hi,

Does C99 strictly require blocking I/O?

Can readers of this forum point to the section
in the C99 specification which state the rules
regarding I/O?

Sincerely,
Seima Rao.
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Issues in building a shared library

abaru...@gmail.com (Arun) — Mon, 19 Mar 2012 18:39:47 UT

Hello,
I am trying to build a shared library called "libjxx.so" using Visual
studio2008 V9.0. The module contains both C & fortran routines. I am
making the C-source as start up project and linking the F-source
against it. I am also linking couple of other libraries called
libm7.lib & libm8.lib. I am getting the following errors concerning

Struct & Arrays & passing to function, and the resulting array of confusion

ernst_b...@sbcglobal.net (Ernst) — Mon, 02 Jan 2012 00:09:16 UT

Hello and thanks for reading.

I like to write C programs as my hobby and I rarely use functions for
my projects simply because most of my efforts are workable in the
domain of main().

I have read much in the past two days and have tried changing my code
but I am not getting it so even though I have searched and read a

Public Resources for C Programming, Particularly Video?

hsa...@gmail.com (haziz) — Mon, 02 Jan 2012 00:09:01 UT

What public or open-courseware resources are available for C programming particularly at an intermediate level? I have actually taken the CS50 course via Harvard Extension so I am looking for other resources. Coverage of data structures using C rather than Java would also be welcome. Prefer video resources (videotaped lectures in particular). Focus on Unix programming at the command line level also welcome. I am also going through K&R to reinforce my comfort with C even though I just finished the formal programming course.

copying structure members shifts by one byte when using memcpy()

navin8...@gmail.com (navy) — Sat, 10 Dec 2011 10:04:21 UT

Hi,

I am working in ubuntu linux 8.04 version and using gcc compiler for
compiling my application.
I am using a function as below

uint8 Message(uint8 u8SignalID, tstControlMessageData
*pstControlMessageData)
{
tstControlMessage stControlMessage;
uint8* char_ptr;
uint8 iCount;

Glue to Re-define a Bunky Function?

vanlu...@iinet.net.au (Modafinil) — Mon, 05 Dec 2011 15:15:54 UT

Hi,

Some code I'm working with uses the C string library function
strrchr(), but my compiler's implementation works in a non-standard
way. It can't seem to point to a string's first '\0' character with a
call like p = strrchr(dest, '\0');

In preference to altering the original code, I would like to somehow

Pointer to &array[-1] - legal?

mjsi...@scriptoriumdesigns.com (KK6GM) — Mon, 05 Dec 2011 15:15:07 UT

I've run into some code that uses this idiom for looping through an
array

some_type *ptr = &some_type_array[0] - 1;

while (*(++ptr) != some_val)
...

What I'm wondering is whether forming the pointer (&some_type_array[0]
- 1) is legal. I realize that this array is never used to access

pointer error

raushanpa...@gmail.com (raushan kumar) — Tue, 29 Nov 2011 03:02:14 UT

Here I have written a program to find the center of tree .It will tell
you the vertex number which is the center of tree. Tree has been
represented
here by using adjacency matrix. In line no 109 i am using an array
of pointers to store the addresses of elements of two dimensional
array.

It showing me segmentation fault in line no 119. I want to know why i

How sizeof works ? Memory map for variable length array of strings

vimal3...@gmail.com (knight) — Fri, 04 Nov 2011 03:26:04 UT

const char *pointerStr[]=
{
"BEST123, ", // 0x00
"Best2233, ", // 0x01
"ABCDEFGH, ", // 0x02
"123456, ", // 0x03
"helloworld, " // 0x04
typedef struct
{
char value;
char name[40];

typedef struct
{
int regMax;
StrInfo info[60];

Size of data types

chiru.0123456...@gmail.com (Chiru Reddy) — Wed, 02 Nov 2011 17:50:27 UT

what will be the size of data types(long, int, char, short) on a 64-
bit architecture?
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Question on: debug printf macro

zig...@libero.it (Enrico) — Fri, 28 Oct 2011 06:59:21 UT

Hi,

I'm writing a C program and I would like to know if the following
thing is feasable?

1) My program is made of 10 files.

2) Each module can print a debug string over the standard output. For
example:

debug_printf (MODULE_1, "The value of temperature is %d",
temperature);
debug_printf (MODULE_2, "I received the following char - %c", ch);

IDE Systems for Windows 7and other problems...

mikiesrunsbaal....@sbcglobal.net (TheGunslinger) — Fri, 28 Oct 2011 06:58:51 UT

Sorry to bother.

I am completing a C Language programming class.

The instructor and I thought that I might be able to complete all the
programming assignments using my IDE system from the C++ class last
semester. (Nokia QT 4 Creator and libraries)

However, the instructor found (and I corrected) some C++ coding

porting tool

bitbucke...@yahoo.com.au (Caviare) — Fri, 28 Oct 2011 06:59:06 UT

My client has 200KLOC of working code on an architecture where char is 8
bits, short is 16 bits, and int and long are 32 bits. They want to port
to an architecture where char, short and int are all 16 bits, and long
is 32 bits. Both architectures are twos complement. The source for the
most part looks reasonably well written C90 code, however I have

Avoiding new line reading a string with readline

zanzibanos...@nospamlibero.it (Carlo Zanziba) — Fri, 28 Oct 2011 06:58:36 UT

Hi,

I'd want to achieve the following effect during an input from terminal
using readline in a C program:

the user types something (the input line), and the input routine does
not go to a new line, rather types something in response and only after
this response the new line is executed.

Call for Proposals - ACCU 2012

dietmar.ku...@gmail.com (Dietmar Kühl) — Fri, 30 Sep 2011 19:47:33 UT

ACCU is a non-profit organisation run by software enthusiasts for
software enthusiasts.

ACCU warmly invites you to propose a session for this leading,
much-loved software development conference.

Call for Proposals - ACCU 2012
April 24-28, 2012. Barcelo Oxford Hotel, Oxford, UK
Submission website: [link]

A couple of questions on evaluation of expressions (I think)

shishir.pan...@gmail.com (shishir) — Wed, 28 Sep 2011 19:44:12 UT

Hi all,

I recently came across the following two code snippets in a test on C.

1.
<...snip..>
int arr[] = {1,2,3,4,5};
int num = 0;

num = arr[1] + (arr[1] = 2);
printf("%d\n", num);
<...snip...>

2.
<....snip...>
int arr[] = {1,2,3,4,5};
int num = 0;
int i = 0;

I/O Error Detection

mikiesrunsbaal....@sbcglobal.net (TheGunslinger) — Sun, 25 Sep 2011 17:30:33 UT

Hi,
I should have asked this sooner rather than later...
I have several functions that require the input of an int, or double.
IF I input a char, these functions go into an infinite loop, and I
have to CTRL-C to quit the program.
Now if this were C++, I could use a try/throw/catch to validate my
input.

Pointers in Two-Dimensional Arrays

bruce.mcgove...@gmail.com (Bruce McGoveran) — Tue, 13 Sep 2011 05:55:46 UT

Hi. Suppose I make the following two-dimensional array declaration:

int a[ROWS][COLS]; ROWS and COLS defined elsewhere

Assume I populate the array thereafter. I now want to iterate through a particular row or column. If I declare an integer pointer (int *p), I gather I can use the following code to iterate through row a[i]:

Use of Letters in C Numerical Constants

bruce.mcgove...@gmail.com (Bruce McGoveran) — Thu, 08 Sep 2011 16:15:29 UT

Hi. I am trying to understand better the circumstances in which, when coding in C, I should append letters to numerical constants. This topic comes up in pretty much every C textbook I look at, though I'm still not clear on the use of these letters. For example, suppose I declare a float and immediately initialize it as follows:

Using non-inline function from inline version

marc.gli...@gmail.com (Marc) — Mon, 15 Aug 2011 16:34:15 UT

Hello,
I have a library that exports a function f. In my header, I want to
provide an inline version of f. And in the implementation of the inline
function, I want to call the library's version of f. Is that possible?
Note that:
* users need to be able to use &f, so I can't just write a macro (and
probably not a static function either);

enums vs. macros

chapte...@yahoo.com (Mark R. Bannister) — Mon, 15 Aug 2011 16:33:15 UT

Hi,
I've been using macros for many years in my programming language.
Here's a sample header file:
[link]
From line 301 you'll see:
etc.
The principle is that my programming language uses registers that can
contain pointers to many different types of structure, and the exact

Dangling Pointer

genius.d...@gmail.com (Sudhanshu Baruntar) — Sat, 06 Aug 2011 05:27:57 UT

Given following
char * swap(char* a){
char *b = "CBA";
a=b;
return a;
int main(){
char *a = "ABC";
a = swap(a);
printf("%s\n", a);
O/p: CBA
What I expected was to have 'a' as dangling reference, and some
garbage output but got this .. :( and its not an assignment. Just let
me know whether I am correct or not.

Solution ?

amardeep.develo...@gmail.com (HumbleWorker) — Sat, 30 Jul 2011 06:49:15 UT

Write a C program to create an array of 10 integer elements. Receive 5
even numbers and 5 odd numbers from the user as input at the keyboard.
While receiving input from the user, following point is to be kept in
mind - If the user enters more than 5 EVEN or ODD numbers in the
array, discard that input, display a warning message on the console

compile C programs for both sunstudio and Visual studio

ehabaziz2...@gmail.com (happytoday) — Mon, 18 Jul 2011 03:49:38 UT

I comile C programs for bothe platforms : sunstudio using cc , visual
studio 6 . Is there a command to differeniate which platform I compile
for . That in order to use the the system command .
For example :
If (unixplatform)
system("clear");
else
system("cls")

Checking Memory Alignment

sopord...@gmail.com (pentup) — Mon, 18 Jul 2011 03:49:23 UT

I need to do a comparison test to see if a particular chunk of memory
is 16-byte aligned, particularly a float pointer. I am currently
working on a 64-bit machine and casting the pointer to a uint64_t to
do the comparison; however, I will want to the ability to run this on
a 32-bit machine and this cast will throw a compiler error. Example of

Problem calling exp10()

bruce.mcgove...@gmail.com (Bruce McGoveran) — Tue, 12 Jul 2011 22:21:24 UT

Hi. I repeatedly receive an "implicit declaration of function" error on the line on which I call exp10() in the following code:
/* A program to understand exponent calls better. */
int
main(void)
{
double e = exp10(10);
printf("%f\n", e);
return 0;
I wrote this code to try an isolate a similar error in another program. I've attempted to compile the code with make, and I can't. I've also tried adding the #define _GNU_SOURCE directive recommended in the man entry for exp10. That didn't help.

Order of operations for promotion rules

ya...@ieee.org (Randy Yates) — Wed, 06 Jul 2011 21:52:46 UT

Consider the following snippet:
int16_t a;
int16_t b;
int32_t c;
c = (int32_t)a * 100 + b * 100;
I believe C's integer promotion rules dictate that the second addend,
"b * 100", will be promoted to an int32_t before adding. However, does
this code guarantee that b will be promoted to int32_t before
multiplying by 100?

'L' suffixing needs

daveo...@aol.com (anInnocent) — Sun, 12 Jun 2011 20:06:47 UT

I'm on a platform where ints are 16 bits and longs are 32 bits (and are the largest possible representation.)
long longVal;
longVal = 1000000;
longVal += (60 * 60);
printf("%ld\r\n",longVal);
longVal = 1000000;
longVal += (60 * 60L);
printf("%ld\r\n",longVal);
longVal = 1000000;
longVal += (long)(60 * 60);

Microsoft c (MC/MSC) for DOS - compatible free old DOS compiler?

tru...@yahoo.co.uk (mike7g) — Wed, 08 Jun 2011 01:54:06 UT

Hi i would like to know, if any of the freely available old DOS c
compilers would be compatible with the very old
microsoft c compiler for DOS (circa 1985/6). This is just a request
for historic information ( i cannot code in c ).
I know it might sound a crazy request, but i have a very old book
which i like the look of ("introducing c Boris Allan") written for old

magic numbers masks on 32 or 64 bits ?

freepo...@gmail.com (Octavio) — Thu, 26 May 2011 19:16:07 UT

Hi,
please, are the following mask hexa numbers coded on 64 or 32 bits ?
<snip>
<snip>
Those are used in bitwise AND operations against register int
variables for exponent and mantissa computing.
But it doesn't compute the exponent as expected.
The related application runs on a x86_64 (64 bits) computer on Linux

using pointers

s...@snafu.de (Samier) — Thu, 26 May 2011 19:15:11 UT

hello,
during programming with strings and some experiences with
segmentations faults (finding that out after using a debugger:) I
thought it would be a better programming style to define variables
this way if possible:
int d ;
char a[10] ;
When using functions which ask for pointers I would use &. That way I

C language & Thread

dipesh2...@gmail.com (Dipesh Rathod) — Wed, 18 May 2011 17:15:40 UT

is Thread Concept apply in C language ?
If Yes then How it's apply....?

Problem with dumping long double

takan...@gmail.com (takanaev) — Wed, 18 May 2011 17:15:25 UT

At the first sorry for my English.
Here I have a problem with following code:
[code]
typedef float real;
typedef double real;
typedef long double real;
#error Error: define FLOAT or DOUBLE or LONG_DOUBLE only
typedef union { real r; unsigned char ca[sizeof(real)]; } utype;
unsigned char get_max_unity(void)

ignoring \0 within char

cup...@gmx.de (sebastian) — Thu, 05 May 2011 16:35:24 UT

Hello,
i try to read out information from a file. there will be sometime
within the read information a charendterminator. is there a possibilty
to ignore this and step to the next character?
gcc options
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Lina ro
4.4.4-14ubuntu5' --with-bugurl=file:///usr/shar e/doc/gcc-4.4/

Question about "mixed declarations and code" in C89/C90

sgb...@googlemail.com (s5n) — Thu, 05 May 2011 16:35:09 UT

Hello, gurus,
i have a question about C89's "declarations before code" policy. (i'm
not challenging the policy, just trying to understand that to my eyes
appears to be an an ambiguity in the definition of "code".)
void foo()
{
int x = bar();
int y;
... do something demonstrative ...
what i'm trying to understand is why the call to bar() is _not_

header files for multiple modules

ethicalb...@hotmail.com (bystander) — Sat, 16 Apr 2011 19:12:23 UT

I have a project with several translation units. Is it customary to
include all function prototypes in one header file or have a separate
header for each module?
bystander

Replace multiples of 3 and 5 with T and F

srikanth0...@gmail.com (srikanth) — Sat, 09 Apr 2011 03:20:36 UT

Hi All,
I am new to c programing. Recently one of my friend attended a
interview and the interviewer asked a question to write a program
which prints 100 numbers and from those 100 numbers replace multiples
of 3 and 5 with T and F.
can any one tell help me out from this.
int main(){
for(inti=1; i<=100; i++)

safety of strncmp

parag.p...@gmail.com (parag) — Sat, 09 Apr 2011 03:20:21 UT

Does the runtime check for the length of the string for strncmp.
For example.
char psarg[2];
strncmp(psarg, "aloha", 5);
Will it lead to memory corruption?
-Parag