10-19-2009
broli,
C does not hide memory pointer information.
"asdf" is a "string literal."
when initializing a char*, "asdf" is seen by the program as a pointer to that location in memory.
The same is not true for other basic types.
int *Bogus = { 0, 1, 2, 3, 4}; - does not work
int Correct[5] = { 0, 1, 2, 3, 4}; does work
malloc() allocates memory on a global heap, and requires a type cast.
using [] allocates memory locally, and the size of this chunk is limited, so don't use brackets for really big arrays.
Two operators will come in handy all the time... "*" and "&"
10 More Discussions You Might Find Interesting
1. Programming
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)
Discussion started by: sarwan
1 Replies
2. Programming
what is far pointer in C (1 Reply)
Discussion started by: useless79
1 Replies
3. What is on Your Mind?
All Sys Administrators,
With due respect I would like to know what should be BEST Things to
do when LEAVING one job , and what Precaution MUST be taken
while taking over new JOB?? Please Discuss in detail the STEP to be
taken for both the TIME ?? (3 Replies)
Discussion started by: vakharia Mahesh
3 Replies
4. Programming
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)
Discussion started by: aaronwong
11 Replies
5. Homework & Coursework Questions
1. List commands
to create the directory hierarchy $HOME/a/b/c
in vi to replace all occurences of TMP with tmp in lines 1 through 10
in vi to replace first occurence of CPU_file with DISK_file at line 15
2. Explain with a very simple example, usage of "ls -a"
3. What do the... (2 Replies)
Discussion started by: jessesaini
2 Replies
6. Shell Programming and Scripting
Q-1
Write a shell script in Unix that lists files from your current working directory
· By modification time when called with lm
· By access time when called with la.
By default, the script should show the listing of all the files in the current directory.
Q-2
Write a... (1 Reply)
Discussion started by: Vishank Parikh
1 Replies
7. Homework & Coursework Questions
Q-1
Write a shell script in Unix that lists files from your current working directory
· By modification time when called with lm
· By access time when called with la.
By default, the script should show the listing of all the files in the current directory.
Q-2
Write a shell script which... (1 Reply)
Discussion started by: Vishank Parikh
1 Replies
8. Programming
When I compile the below code, I am getting error as
template<typename T> T AddFun(T i, T j) {
return i + j;
}
template<> T* AddFun<T*>(T* i, T* j) {
return new T(*i + *j);
}
int main() {
int n = AddFun<int>(10, 20);
int i = 10, j = 20;
int* p = AddFun<int*>(&i,... (1 Reply)
Discussion started by: royalibrahim
1 Replies
9. Homework & Coursework Questions
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known data:
In the command line I will be given files or words which will be USER ID's or a file of USER ID's. I am to let... (4 Replies)
Discussion started by: ByronicX
4 Replies
10. UNIX for Dummies Questions & Answers
Hello all im currently working on this assignment and a little stump on how to check for an argument heres the instructions:
Step 4:
Modify your script so that if there is an argument called TestError you display the following error message with your usage statement.
TestError found
Example:... (1 Reply)
Discussion started by: bsn3971
1 Replies
LEARN ABOUT HPUX
xtrealloc
XtRealloc() XtRealloc()
Name
XtRealloc - change the size of an allocated block of storage.
Synopsis
char *XtRealloc(ptr, num);
char *ptr;
Cardinal num;
Inputs
ptr Specifies a pointer to memory allocated with XtMalloc(), XtCalloc(), or XtRealloc(), or NULL.
num Specifies the new number of bytes of memory desired in the block.
Returns
A pointer to allocated memory.
Description
XtRealloc() changes the size of the block of allocated memory pointed to by ptr to be at least num bytes large. In order to make this size
change, it may have to allocate a new block of memory and copy the contents of the old block (or as much as will fit) into the new block.
If it allocates a new block of memory, it frees the old block. In either case, it returns a pointer to a block of memory which is of the
requested size. If there is insufficient memory to allocate the new block, XtRealloc() terminates by calling XtErrorMsg().
If ptr is NULL, XtRealloc() simply calls XtMalloc() to allocate a block of memory of the requested size.
Usage
Note that XtRealloc() may move the contents of your allocated memory to a new location; the return value may or may not be the same as ptr.
Not all memory can be safely reallocated. If there are multiple pointers to a block of memory scattered through out an application (such
as pointers to a widget record), then reallocating that memory is not safe, because all pointers to it cannot be updated. Other memory
(such as the array of children maintained privately by the Composite widget class) can be safely updated because there should be only one
pointer to it in the application (in this case the pointer is the composite.children field of the widget). These cautions are no different
than those required with the standard realloc() function.
In most cases, you will have to cast the return value of XtRealloc() to an appropriate pointer type.
Note that because XtRealloc() behaves like XtMalloc() when passed a NULL pointer, (something that realloc() does not do), you don't have to
write special case code to allocate the first chunk of memory with XtMalloc() and subsequent chunks with XtRealloc(); you can simply use
XtRealloc() everywhere.
Memory allocated with XtRealloc() must be deallocated with XtFree(). The function XtRealloc() is implemented by the Toolkit independently
of the particular environment, so programs ported to a system not supporting malloc will still work.
See Also
XtCalloc(1), XtFree(1), XtMalloc(1), XtNew(1), XtNewString(1).
Xt - Memory Allocation XtRealloc()