Whilst creating the function readjust_descr I have stumble across what may be a problem or
something that might just work. I was hoping someone could look at the code below and tell me
if readjust_descr will clear all null pointers from the structure descr_list.
While I am here I might as well ask this also. Thanks a bunch.
Can you show me how to access the second array of a pointer
that calloc returns if I allocated two elements. calloc() allocates memory for an array of nmemb elements.
The man page says it returns a pointer to the allocated member.
I am facing a problem in replacing the file contents by iterating through the list.
My present code:
Code:
#!/bin/bash#
TFILE="/tmp/vinay/testb_1.txt"
while read linedo
aline="$line"
echo $aline
code=`echo $aline|cut -d ',' -f1`
country=`echo $aline|cut -d... (5 Replies)
hi all,
i am writing a ksh script, i am logging into an oracle db via sqlplus and running a select statement but i dont know how i can store the results from the sql so i can iterate over it and do more operations over it. I dont want to write a stored procedure with a cursor since i need to... (2 Replies)
Hey everyone.
Is it possible to use two arrays in a loop?
Basically what I am trying to do is iterate through the elements in an array, and, based on a condition, use the current position in the array to point to that index in the array. Here's the loop structure I'm looking for:
... (1 Reply)
Hello all,
I have a confusion with calloc function :
wz. the difference between the following 2 statemnts:
char *ptr;
char = (char*)calloc(num, sizeof(char));
char = (char*)calloc(num, sizeof(char*));
Am really confused!!!!!
---------- Post updated at 09:32 AM... (1 Reply)
Hello, I am working on a coding project for a class and to test the program I have created, I have come up with 100 different test cases. The program takes four text files as input, so each of the test cases is contained in a folder with four files.
I have a folder called 'tests', within which... (1 Reply)
Hi,
I've recently started using Awk commands as i need it to pull information out of a file and give me the mean value of a series of numbers. Here is the code i run on my Infile and it works just fine.
awk '{if ($1 == "Mam189") print $0}' Infile | awk '{if ($1 != $2) print $0}' | awk... (5 Replies)
Hi , experts.
I work on Linux station (RedHat 5.7), regular user, but have root password.
%> uname -a
Linux ran1log06 2.6.18-238.1.1.el5 #1 SMP Tue Jan 4 13:32:19 EST 2011 x86_64 x86_64 x86_64 GNU/Linux
%> cat /etc/issue
Red Hat Enterprise Linux Client release 5.7 (Tikanga)
Kernel \r on... (5 Replies)
I need to run the same awk function over an entire directly of files.
This is the awk:
awk '{$(NF+1)=1}1'
Is there a way that I can run this command once over all of the files, along the lines of:
awk '{$(NF+1)=1}1' *
so that I do not have to run this several times?
My main concern is... (2 Replies)
Hi,
I am trying to do something similar to the for loop example from KSH For Loop Array: Iterate Through Array Values
$: cat y.ksh
#!/bin/ksh
# set array called nameservers
set -A nameservers 192.168.1.1 192.168.1.5 202.54.1.5
# print all name servers
for i in ${nameservers}
do
... (3 Replies)
Discussion started by: newbie_01
3 Replies
LEARN ABOUT REDHAT
free
MALLOC(3) Linux Programmer's Manual MALLOC(3)NAME
calloc, malloc, free, realloc - Allocate and free dynamic memory
SYNOPSIS
#include <stdlib.h>
void *calloc(size_t nmemb, size_t size);
void *malloc(size_t size);
void free(void *ptr);
void *realloc(void *ptr, size_t size);
DESCRIPTION
calloc() allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated memory. The memory is
set to zero.
malloc() allocates size bytes and returns a pointer to the allocated memory. The memory is not cleared.
free() frees the memory space pointed to by ptr, which must have been returned by a previous call to malloc(), calloc() or realloc(). Oth-
erwise, or if free(ptr) has already been called before, undefined behaviour occurs. If ptr is NULL, no operation is performed.
realloc() changes the size of the memory block pointed to by ptr to size bytes. The contents will be unchanged to the minimum of the old
and new sizes; newly allocated memory will be uninitialized. If ptr is NULL, the call is equivalent to malloc(size); if size is equal to
zero, the call is equivalent to free(ptr). Unless ptr is NULL, it must have been returned by an earlier call to malloc(), calloc() or
realloc().
RETURN VALUE
For calloc() and malloc(), the value returned is a pointer to the allocated memory, which is suitably aligned for any kind of variable, or
NULL if the request fails.
free() returns no value.
realloc() returns a pointer to the newly allocated memory, which is suitably aligned for any kind of variable and may be different from
ptr, or NULL if the request fails. If size was equal to 0, either NULL or a pointer suitable to be passed to free() is returned. If real-
loc() fails the original block is left untouched - it is not freed or moved.
CONFORMING TO
ANSI-C
SEE ALSO brk(2), posix_memalign(3)NOTES
The Unix98 standard requires malloc(), calloc(), and realloc() to set errno to ENOMEM upon failure. Glibc assumes that this is done (and
the glibc versions of these routines do this); if you use a private malloc implementation that does not set errno, then certain library
routines may fail without having a reason in errno.
Crashes in malloc(), free() or realloc() are almost always related to heap corruption, such as overflowing an allocated chunk or freeing
the same pointer twice.
Recent versions of Linux libc (later than 5.4.23) and GNU libc (2.x) include a malloc implementation which is tunable via environment vari-
ables. When MALLOC_CHECK_ is set, a special (less efficient) implementation is used which is designed to be tolerant against simple
errors, such as double calls of free() with the same argument, or overruns of a single byte (off-by-one bugs). Not all such errors can be
protected against, however, and memory leaks can result. If MALLOC_CHECK_ is set to 0, any detected heap corruption is silently ignored;
if set to 1, a diagnostic is printed on stderr; if set to 2, abort() is called immediately. This can be useful because otherwise a crash
may happen much later, and the true cause for the problem is then very hard to track down.
Linux follows an optimistic memory allocation strategy. This means that when malloc() returns non-NULL there is no guarantee that the mem-
ory really is available. In case it turns out that the system is out of memory, one or more processes will be killed by the infamous OOM
killer.
GNU 1993-04-04 MALLOC(3)