i have a function:
char *pcCityIdToCountryName(ADMIN_DB_DATA *pstHEader, unit uiCityID)
this returns a pointer to CountryName if cityId is given.
to retrieve countryname i give:
char *CountryName;
CountryName = pcCityIdToCountryName(..................);
but when i compile it is giving :... (5 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)
Hi,
I am trying to reverse a string using the following program utilizing the Exclusive OR bit operation:
int main() {
char str = "Quraish";
char *p = str, temp;
char *q = str + strlen(str) - 1;
while ( p != q ) {
if (*p != *q) {
*p ^= *q; *q ^= *p; *p ^= *q;... (1 Reply)
Hi.
Problem: I have to parse the payload of a packet. The payload could be in Big Endian Format (network byte order) or little. That depends on a flag present in the header of the packet.
Solution: A horrible solution could be to check for that flag everytime I have to read a field in the... (11 Replies)
Hi,
What is the difference in the following two awk one-liners?
awk -F, '{s++} END {if (s == 1 && $4 > "09:10:00") {print $2, $4}}' f1
awk -F, '{s++} s == 1 && $4 > "09:10:00" {print $2, $4}' f1
Even though, all the 2nd column values have duplicate records, the first code does not give any... (4 Replies)
if i create an array of pointers to a structure "struct node" as:
struct node *r;
and create "n" number of "linked lists" and assign it to the various struct pointers r using some function with a return type as structure pointer as:
r=multiplty(.......) /*some parameters*/
is... (2 Replies)
Hi,
In the following perl code:
#!/usr/bin/perl -w
if (open(FILE, "< in_file")) {
while (<FILE>) {
chomp($_);
if ($_ =~ /patt$/) {
my $f = (split(" ", $_));
print "$f\n";
}
}
close FILE;
}
Why changing the "FILE" as... (4 Replies)
Have difficulty to understand this pure C code to only print vowels twice from input string. Questions are commented at the end of each place.
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
/*
*Demonstrate the use of dispatch tables
*/
/*Print a char... (11 Replies)
I am passing a char* to the function "reverse" and when I execute it with gdb I get:
Program received signal SIGSEGV, Segmentation fault.
0x000000000040083b in reverse (s=0x400b2b "hello") at pointersExample.c:72
72 *q = *p;
Attached is the source code.
I do not understand why... (9 Replies)
Discussion started by: jose_spain
9 Replies
LEARN ABOUT DEBIAN
bup-margin
bup-margin(1) General Commands Manual bup-margin(1)NAME
bup-margin - figure out your deduplication safety margin
SYNOPSIS
bup margin [options...]
DESCRIPTION
bup margin iterates through all objects in your bup repository, calculating the largest number of prefix bits shared between any two
entries. This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids.
For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45. That means a 46-bit
hash would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by
its first 46 bits.
The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects. Since SHA-1 hashes have 160 bits,
that leaves 115 bits of margin. Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits
with far fewer objects.
If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see if
you're getting dangerously close to 160 bits.
OPTIONS --predict
Guess the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer
from the guess. This is potentially useful for tuning an interpolation search algorithm.
--ignore-midx
don't use .midx files, use only .idx files. This is only really useful when used with --predict.
EXAMPLE
$ bup margin
Reading indexes: 100.00% (1612581/1612581), done.
40
40 matching prefix bits
1.94 bits per doubling
120 bits (61.86 doublings) remaining
4.19338e+18 times larger is possible
Everyone on earth could have 625878182 data sets
like yours, all in one repository, and we would
expect 1 object collision.
$ bup margin --predict
PackIdxList: using 1 index.
Reading indexes: 100.00% (1612581/1612581), done.
915 of 1612581 (0.057%)
SEE ALSO bup-midx(1), bup-save(1)BUP
Part of the bup(1) suite.
AUTHORS
Avery Pennarun <apenwarr@gmail.com>.
Bup unknown-bup-margin(1)