I have a function to which I will pass a struct ID and it will return me a string.
I will pass a pointer to store the name string and that pointer will be allocated memory by the function called.
The function ConvertIDToName() fails to store the allocated memory address in the void pointer.
I am unable to assign memory in the pointer and it gives me error from 3rd statement of function ConvertIDToName():
What am I doing wrong?
---------- Post updated at 02:33 AM ---------- Previous update was at 02:32 AM ----------
I missed the simple thing of typecasting the void pointer before using it.
This solves the issue:
First and foremost, this is not a homework for your information. I'm just new to using c-shell programming and I just wanted to make my life easier @ work.
Say, the file contains the following:
ID FILE NO. SL VP
1 1 22 33
1 2 ... (3 Replies)
Hello all
im trying to build function that will return void function pointer
what is mean is ( not working )
the main function
void * myClass::getFunction(int type){
if(type==1)
return &myClass::Test1;
if(type==2)
return &myClass::Test2;
}
void myClass::Test1(){... (1 Reply)
What is the difference between f(...) , f(void),f()
I know that f(void) doesn't take any parameters, but what about f() and f(...) Does the last call of function even exists? (2 Replies)
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)
N00B here. This function would be easier using a char pointer along with free. But I wish to learn how to use char static pointers (they do not require free, right ?).
How do I erase the content of a static pointer ? Terminating the string works but the static pointer's content is not being... (4 Replies)
i am trying to convert void pointer to pthread_t on hpux-itanium 64 bit which fails as below
"src/file.cpp", line 88: error #2171: invalid type conversion
pthread_t tid = reinterpret_cast<pthread_t>(m_threadId);
1 error detected in the compilation of "src/file.cpp"
... (0 Replies)
hi guys!
Is there such a thing as double void pointer dynamic allocation?
And if so is it something like this?
int n;
void** a;
a=malloc(n*sizeof(void*)); (12 Replies)
Discussion started by: vlm
12 Replies
LEARN ABOUT REDHAT
memalign
POSIX_MEMALIGN(3) Linux Programmer's Manual POSIX_MEMALIGN(3)NAME
posix_memalign, memalign, valloc - Allocate aligned memory
SYNOPSIS
#include <stdlib.h>
int posix_memalign(void **memptr, size_t alignment, size_t size);
void *memalign(size_t boundary, size_t size);
void *valloc(size_t size);
DESCRIPTION
The function posix_memalign() allocates size bytes and places the address of the allocated memory in *memptr. The address of the allocated
memory will be a multiple of alignment, which must be a power of two and a multiple of sizeof(void *).
The obsolete function memalign() allocates size bytes and returns a pointer to the allocated memory. The memory address will be a multiple
of boundary, which must be a power of two.
The obsolete function valloc() allocates size bytes and returns a pointer to the allocated memory. The memory address will be a multiple
of the page size. It is equivalent to memalign(sysconf(_SC_PAGESIZE),size).
For all three routines, the memory is not zeroed.
RETURN VALUE
memalign() and valloc() return the pointer to the allocated memory, or NULL if the request fails.
posix_memalign() returns zero on success, or one of the error values listed in the next section on failure. Note that errno is not set.
ERRORS
EINVAL The alignment parameter was not a power of two, or was not a multiple of sizeof(void *).
ENOMEM There was insufficient memory to fulfill the allocation request.
NOTES
posix_memalign() verifies that alignment matches the requirements detailed above. memalign() may not check that the boundary parameter is
correct.
POSIX requires that memory obtained from posix_memalign() can be freed using free(). Some systems provide no way to reclaim memory allo-
cated with memalign() or valloc() (because one can only pass to free() a pointer gotten from malloc(), while e.g. memalign() would call
malloc() and then align the obtained value). GNU libc allows memory obtained from any of these three routines to be reclaimed with free().
GNU libc malloc() always returns 8-byte aligned memory addresses, so these routines are only needed if you require larger alignment values.
AVAILABILITY
The functions memalign() and valloc() have been available in all Linux libc libraries. The function posix_memalign() is available since
glibc 2.1.91.
CONFORMING TO
The function valloc() appeared in 3.0 BSD. It is documented as being obsolete in BSD 4.3, and as legacy in SUSv2. It no longer occurs in
SUSv3. The function memalign() appears in SunOS 4.1.3 but not in BSD 4.4. The function posix_memalign() comes from POSIX 1003.1d.
SEE ALSO malloc(3), free(3), getpagesize(2), brk(2)GNU 2001-10-11 POSIX_MEMALIGN(3)