1) They probably differ in being constants or non-constants.
3) It's "3d" because you have an extra pointer in the way. Every level of pointers requires another dereferencing operation to access it. One level pointer requires one. Two level pointer requires two. Three level pointer requires three. 97 level pointer requires 97. That is the pattern.
The first dereferencing operation gets rid of is x itself; once you do so, you are essentially accessing y. The next level of pointers points to individual rows inside y. The last level gets you an individual cell in that row.
The diagram is x -> y -> row -> column.
These 2 Users Gave Thanks to Corona688 For This Post:
void main()
{
int a={1,2,3,4,5,6,7,8,9,10};
int *p=a;
int *q=&a;
cout<<q-p+1<<endl;
}
The output is 10, how?
if we give cout<<q it will print the address, value won't print....
if we give cout<<p it will print the address, value won't print....
p has the base addr; q... (1 Reply)
All ..
I am having a pointer array . And trying to store the addess into that pointer array . please see below the problem i faced
code:
int cnt1;
char *t_array;
char *f_array;
for(cnt1=0; cnt1<1000; cnt1++)
{
t_array =... (1 Reply)
If one wants to get a start address of a array or a string or a block of memory via a function, there are at least two methods to achieve it:
(1) one is to pass a pointer-to-pointer parameter, like:
int my_malloc(int size, char **pmem)
{
*pmem=(char *)malloc(size);
if(*pmem==NULL)... (11 Replies)
Hi all,
Can anyone provide help with getting the right syntax regarding array/pointers in C in the following code? Can't locate a specific example which clarifies this...
Say I declare a typedef to an array of pointers to some type...
/**
* An array of ptrs to sections
*/
typedef... (4 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)
This code is to print out the program name and arguments list one by one:
1 #include<stdio.h>
2
3 void main(int argc, char *argv)
4 {
5 int iCount = 0;
6 while (iCount < argc) {
7 printf("argc:%d\t%s\n",iCount, argv);
8 ... (14 Replies)
Hello,
The purpose of the program is to print a sub string from the prompt inputs. I do not understand why char pointer does not work but char array will for line 40 and Line 41.
./a.out thisisatest 0 8
substring = "thisisat"And my code is:
#include <stdio.h>
#include <stdlib.h>
#include... (29 Replies)
how to copy content of character pointer to character array in c programming..
char *num;
char name=num; (1 Reply)
Discussion started by: zinat
1 Replies
LEARN ABOUT BSD
alphasort
SCANDIR(3) Library Functions Manual SCANDIR(3)NAME
scandir, alphasort - scan a directory
SYNOPSIS
#include <sys/types.h>
#include <sys/dir.h>
scandir(dirname, namelist, select, compar)
char *dirname;
struct direct *(*namelist[]);
int (*select)();
int (*compar)();
alphasort(d1, d2)
struct direct **d1, **d2;
DESCRIPTION
Scandir reads the directory dirname and builds an array of pointers to directory entries using malloc(3). It returns the number of entries
in the array and a pointer to the array through namelist.
The select parameter is a pointer to a user supplied subroutine which is called by scandir to select which entries are to be included in
the array. The select routine is passed a pointer to a directory entry and should return a non-zero value if the directory entry is to be
included in the array. If select is null, then all the directory entries will be included.
The compar parameter is a pointer to a user supplied subroutine which is passed to qsort(3) to sort the completed array. If this pointer is
null, the array is not sorted. Alphasort is a routine which can be used for the compar parameter to sort the array alphabetically.
The memory allocated for the array can be deallocated with free (see malloc(3)) by freeing each pointer in the array and the array itself.
SEE ALSO directory(3), malloc(3), qsort(3), dir(5)DIAGNOSTICS
Returns -1 if the directory cannot be opened for reading or if malloc(3) cannot allocate enough memory to hold all the data structures.
4.2 Berkeley Distribution September 17, 1985 SCANDIR(3)