The pragma directive lets you alter the packing of structures but has no affect on ordinary variables. Also it is non-portable and should not be used in code that will be deployed to multiple OSes AIX HPUX Solaris Linux. Output below is from an AIX machine...
Output...
we know that sizeof never returns zero when used with structure
then why in this case it is returning zero
struct foo
{
char c;
};
void main()
{
struct foo f;
cout<<sizeof(f);
}
i am working on solaris 5.8
isn't the above function should return the size of empty structure (7 Replies)
Hello Groups
I am trying to find out ways of comparing a value from a 'c' structure to a value in another 'C' structure. the 'C' structure can be a List or liked list as it contains lot many records.
if we loop it in both the structures it is going to consume time.
I am looking for a simple... (3 Replies)
Hi,
I have a following problem in C.
I have a function A in which I used to call another function (function B) and pass an array of values through array variable by using below:-
foo=functionB(array);
In functionB, i used to just return some "values" (e.g return num;) in order to pass... (1 Reply)
The below code throws the error, since the size of x = 19 is not passed to the cstrCopy function.
using namespace std;
static void cstrCopy(char *x, const char*y);
int main ()
{
char x;
const string y = "UNIX FORUM";
cstrCopy(x,y.c_str());
return 0;
}
void cstrCopy(char *x,... (3 Replies)
Hi,
There are some bewildering sizeof() questions I have in my mind. Could anyone shed some light on this?
int main() {
printf("%d\n", sizeof(main)); // Ans: 1
}
That is, the sizeof() a function identifier though it is treated internally as a pointer gives 1 byte always, why?
... (5 Replies)
Hi,
I have defined the class and call the sizeof(object to class) to get the size.
# include <iostream>
# include <iomanip>
using namespace std;
class sample
{
private:
int i;
float j;
char k;
public:
sample()
{
} (2 Replies)
if i create an array of pointers to a structure "struct node" as:
struct node *r;
and create "n" number of "linked lists" and assign it to the various struct pointers r using some function with a return type as structure pointer as:
r=multiplty(.......) /*some parameters*/
is... (2 Replies)
Hai
how to find size of a file??
ex : /home/kiran/pdk/sample/calibre this is a path
In that I have to find size of a files in side a calibre(it is the folder) like .results or .summary (1 Reply)
Ignoring other considerations for a moment and in general ...
Would there be a difference in result (dot oh or execution) of:
A.
strncpy( a, b, sizeof(a) );
vs.
B.
c = sizeof(a);
strncpy( a, b, c );
My general understanding is (at least I think my understanding is) that... (10 Replies)
Discussion started by: GSalisbury
10 Replies
LEARN ABOUT NETBSD
sysinfo
SYSINFO(2) Linux Programmer's Manual SYSINFO(2)NAME
sysinfo - return system information
SYNOPSIS
#include <sys/sysinfo.h>
int sysinfo(struct sysinfo *info);
DESCRIPTION
sysinfo() returns certain statistics on memory and swap usage, as well as the load average.
Until Linux 2.3.16, sysinfo() returned information in the following structure:
struct sysinfo {
long uptime; /* Seconds since boot */
unsigned long loads[3]; /* 1, 5, and 15 minute load averages */
unsigned long totalram; /* Total usable main memory size */
unsigned long freeram; /* Available memory size */
unsigned long sharedram; /* Amount of shared memory */
unsigned long bufferram; /* Memory used by buffers */
unsigned long totalswap; /* Total swap space size */
unsigned long freeswap; /* Swap space still available */
unsigned short procs; /* Number of current processes */
char _f[22]; /* Pads structure to 64 bytes */
};
In the above structure, the sizes of the memory and swap fields are given in bytes.
Since Linux 2.3.23 (i386) and Linux 2.3.48 (all architectures) the structure is:
struct sysinfo {
long uptime; /* Seconds since boot */
unsigned long loads[3]; /* 1, 5, and 15 minute load averages */
unsigned long totalram; /* Total usable main memory size */
unsigned long freeram; /* Available memory size */
unsigned long sharedram; /* Amount of shared memory */
unsigned long bufferram; /* Memory used by buffers */
unsigned long totalswap; /* Total swap space size */
unsigned long freeswap; /* Swap space still available */
unsigned short procs; /* Number of current processes */
unsigned long totalhigh; /* Total high memory size */
unsigned long freehigh; /* Available high memory size */
unsigned int mem_unit; /* Memory unit size in bytes */
char _f[20-2*sizeof(long)-sizeof(int)];
/* Padding to 64 bytes */
};
In the above structure, sizes of the memory and swap fields are given as multiples of mem_unit bytes.
RETURN VALUE
On success, sysinfo() returns zero. On error, -1 is returned, and errno is set to indicate the cause of the error.
ERRORS
EFAULT info is not a valid address.
VERSIONS
sysinfo() first appeared in Linux 0.98.pl6.
CONFORMING TO
This function is Linux-specific, and should not be used in programs intended to be portable.
NOTES
All of the information provided by this system call is also available via /proc/meminfo and /proc/loadavg.
SEE ALSO proc(5)COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the
latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
Linux 2017-09-15 SYSINFO(2)