the spaceship operator, <=>, is a comparison function, for numeric data only. It compares elements in the input array, @unsorted. The output of the sort call is written to the array @sorted. If no comparison function statement was entered (a blank), then sort works on the @unsoted array as letters of the alphabet, not numbers.
$a and $b are individual elements in the unosrted array - in this case numbers
If element $a is equal to element $b, then it returns 0; if $a is less than $b it returns -1; if $a is greater it returns +1 .
So the general statement is:
Internally perl sort calls a standard C library function, qsort for doing the comparisons and reordering over and entire array -or at least it did years ago. qsort(3): sort array - Linux man page
These 3 Users Gave Thanks to jim mcnamara For This Post:
Hi Friends,
Can any of you explain me about the below line of code?
mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`
Im not able to understand, what exactly it is doing :confused:
Any help would be useful for me.
Lokesha (4 Replies)
Hi Everyone,
# cat a.txt
a;b;c;64O
a;b;c;d;ee;f
# cat a.pl
#!/usr/bin/perl
use strict;
use warnings;
my $tmp3 = ",,a,,b,,c,,d,,e,,f,,";
open(my $FA, "a.txt") or die "$!";
while(<$FA>) {
chomp;
my @tmp=split(/\;/, $_);
if ( ($tmp =~ m/^(64O)/i) || ($tmp... (3 Replies)
I am running a program written in perl script and it is stopped with "Out of memory!" error. This is very strange because at the time then the program is aborted, it only used 4GB RAM and there are still 30GB free physical memory left in the system. I check the perl script and found the program... (3 Replies)
I need to sort the following file by the rhdiskpower devices in the last column:
Total_MB Free_MB OS_MB Name Failgroup Library Label UDID Product Redund Path
1024 851 1024 OCRVOT1_0000 OCRVOT1_0000 System UNKNOWN ... (3 Replies)
Hi,
I have line in input file as below:
3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
My expected output for line in the file must be :
"1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL"
Can someone... (7 Replies)
I have seen something like this in a perl code:
$_ =~ s/__FD_PRN_/\\(/g
What does this "__FD_PRN_" means. I have searched google but was not able to find any info regarding this. Appreciate if some one can refer to a link for these characters. From comments/code it used to substitue "(" with... (3 Replies)
Hi All,
I have 2 pipe delimited files viz., file_old and file_new. I'm trying to compare these 2 files, and extract all the different rows between them into a new_file.
comm -3 < sort file_old < sort file_new > new_file
I am getting the below error:
-ksh: sort: cannot open
But if I do... (7 Replies)
Hello.
System : opensuse leap 42.3
I have a bash script that build a text file.
I would like the last command doing :
print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt
where :
print_cmd ::= some printing... (1 Reply)
Discussion started by: jcdole
1 Replies
LEARN ABOUT DEBIAN
qsort
QSORT(3) Linux Programmer's Manual QSORT(3)NAME
qsort, qsort_r - sort an array
SYNOPSIS
#include <stdlib.h>
void qsort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *));
void qsort_r(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *, void *),
void *arg);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
qsort_r(): _GNU_SOURCE
DESCRIPTION
The qsort() function sorts an array with nmemb elements of size size. The base argument points to the start of the array.
The contents of the array are sorted in ascending order according to a comparison function pointed to by compar, which is called with two
arguments that point to the objects being compared.
The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respec-
tively less than, equal to, or greater than the second. If two members compare as equal, their order in the sorted array is undefined.
The qsort_r() function is identical to qsort() except that the comparison function compar takes a third argument. A pointer is passed to
the comparison function via arg. In this way, the comparison function does not need to use global variables to pass through arbitrary
arguments, and is therefore reentrant and safe to use in threads.
RETURN VALUE
The qsort() and qsort_r() functions return no value.
VERSIONS
qsort_r() was added to glibc in version 2.8.
CONFORMING TO
The qsort() function conforms to SVr4, 4.3BSD, C89, C99.
NOTES
Library routines suitable for use as the compar argument to qsort() include alphasort(3) and versionsort(3). To compare C strings, the
comparison function can call strcmp(3), as shown in the example below.
EXAMPLE
For one example of use, see the example under bsearch(3).
Another example is the following program, which sorts the strings given in its command-line arguments:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static int
cmpstringp(const void *p1, const void *p2)
{
/* The actual arguments to this function are "pointers to
pointers to char", but strcmp(3) arguments are "pointers
to char", hence the following cast plus dereference */
return strcmp(* (char * const *) p1, * (char * const *) p2);
}
int
main(int argc, char *argv[])
{
int j;
if (argc < 2) {
fprintf(stderr, "Usage: %s <string>...
", argv[0]);
exit(EXIT_FAILURE);
}
qsort(&argv[1], argc - 1, sizeof(char *), cmpstringp);
for (j = 1; j < argc; j++)
puts(argv[j]);
exit(EXIT_SUCCESS);
}
SEE ALSO sort(1), alphasort(3), strcmp(3), versionsort(3)COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2012-03-08 QSORT(3)