Programming :: Using /dev/random To Generate Double?
Mar 6, 2010
I need to generate random numbers using /dev/random in C. The numbers should be of type double (64-bit floating point).The functionality should be equal to linux command "od -An -N8 -t fD /dev/random", but written in C.The prototype should be "double drand(void);".
A script to generate random dates. It uses the year range 2006-2009, and truncates every month of the year to an ordinary February's 28 days, but otherwise it's pretty solid and safe.
Not only that but I need tons and tons of them generated, and I need it to be totally random each time.
Code: matthew@mvm:/h/misc> cat a #!/bin/bash for i in {1..5}; do echo $RANDOM
[Code]....
There you can see that it is the same number. It does that every time!! Grrr. The strange thing is each time I manually type [or copy & paste] it into the terminal, it gives random [not static, like I am getting from my script] results.
The reason I want this is because I am making a script where this line will randomly go up or down [depending on if the random number is 1 or 0].
List of 77 lines with the names of movies. For ease, let's say it's in a text file. What I want is a command line argument I can pass that'll read each line and pick one of those 77 lines at random, except I can't figure out how to do this. Is there a program I can just pipe the output of 'cat listofmovies.txt' to?
I want to generate a temporary random list from a directory of files and then determine the size of an arbitrary block of files from this list (say 1-25 or 26-50) and add their names to a file along with some other info for each name. I can generate a random list with file sizes like this: ls -l | sort -R | cut -d " " -f 6 but i'm not sure how to add up the sizes of just a certain block of these files and at the same time save the file names.
Since I enjoyed Gnome shell with Ubuntu 9.10 (but Ubuntu runs too slow on this computer for my druthers), I thought it would be fun to check out gnome shell on 11.3. I thought that since my 11.3 has gnome 2.30, that the gnome shell in the software manager would be a concomitant version, so I installed it. I then followed the directions given in the second posting of Enabling Gnome Shell in 11.3?
When I logged back in, I selected Gnome 3 Preview [even though I hadn't thought that that was what I'd installed -- (has openSUSE retired all older versions of Gnome shell?)]. The desktop won't boot (I don't know what the correct way of saying it is). The splash shows, but the icons just intermittently flash off and on at random intervals, never quite making it all the way "on." When I right click the bottom of the screen, I can select "terminal" (when I can accurately coordinate my double-click with the random, intermittent flashing), but then the terminal also does the random, intermittent flashing as well. So I can never get anything typed in. When I reboot, there's no login box.
In bash I need to use some equivalent of double quotes inside double quotes (or the other way around.)I need to run the following statement to get the output of foo and store it in a variable while passing foo the $file which probably contains spaces.
Code: variable=$(foo "$file") The problem is that foo might return an empty string and if it does I need to catch it
Does anybody know how to generate excel charts from C, or if it's possible at all?
For example, if I had 2 arrays that I wanted to export to excel and graph against each other. I know how to export it to a csv file, that's no problem, but I have no idea where to start with generating a graph of the data. I can't seem to find any examples anywhere.
I'd appreciate if someone could point me in the right direction.
Just a simple example to show you what I mean code...
I have a file, two columns, first column has a list of 15000 (yes 15k) unique codes, second column has the afilliate codes of 60 locations repeated to fill out the 15000 rows of unique codes. I need to produce a nice neat paper voucher which will fit onto A6 (1/4 A4) and is ready to print. Each voucher has the unique code and corresponding location. So far I am thinking PHP will do the job. This does it somewhat, but doesn't let be split the fields between the ",". I did this so far in PHP
I am trying to generate pdf in thai language. i have installed thai package (extension in babel package). It is finally generating pdf in thai. but thai string are cming very long as compared to original string given in .tex file.
I want to automate my System-installation. So i try to make a Script that will generate the /etc/motd. Now i have the Problem that the script has some variables and after the "Hostname, OS, HW, IP" the "stars" are anyware, but not there they should. The most problem is the $OS this string can verry long or verry short be. Fedora release 12 (Constantine) or RedHat 5.4 i can do that after the variables place the "stars" on the write position?
I have some c++ code and want to generate class diagrams using some tool which would scan the c++ code and generate diagrams. Is there any such open source tool to be used on linux machine?
I'm trying to write a bash script that has to extract values from a csv file. Problem is there are lines like this:a,b,c,"dd,dd,dd",e,f,gI'm using awk to extract the values but when I try it extract value 4 with awk I get:"ddinstead of:"dd,dd,dd"Does anyone know how to get awk to ignore commas within double quotes?
in c/c++, double is usually 8 bytes. It has a 52-bit mantissa (or significand, or base), an 11-bit exponent, and a 1-bit sign. My question is: is the mantissa a 52-bit integer? Or is the decimal point just after the first bit. Meaning: if the mantissa was 1000110011100011 (in binary) would that make the value of the mantissa (assuming the exponent was 0) 1000110011100011, or 1.000110011100011? (in binary)
can i get the ocuurance of left click-right click-double click?i need the time of ocurance and the click(left-right-double) that happend.any software?any clue..i need it in linux environment(kde or gnome)
I want to write a program in C which will generate a maze randomly and find the solution for it ..
The idea behind is in [url]
How the 16 bit integer is stored in a variable..Earlier I wrote a program on trees and displayed it using dotty.. Is there any such tool to display a maze..I am using ubuntu 10.04.
i have spotted that script (something similar that i am looking for)
[URL]
and i just dont know how to use it.I am not a programmer myself and probably no need for learning that just to create one script! modify "wje_lq" script and run it. thing like : "Just redirect standard output to a file in the normal manner" ? and all this
I.Comment out the first definition of *character-set*, by adding a semicon at the beginning of the line.
II.Uncomment the second definition, which just uses "ABC", by removing the semicolon from the beginning of the line.
III.Comment out the first definition of *word-length*.
IV.Uncomment the second definition, which uses a word length of four.
i would like to generate :
10-character combinations of the following characters (lowercase) 23456789abcdef with no more then 3 same letters repeates no metter side by side or within one line (sequence) so lets say
I'm trying to write an extension to PHP which means coding in C. I'm really really rusty at C coding and was never very good at it.
Can anyone propose an efficient, safe, and [hopefully] future-proof way of reversing a double? Keep in mind that it should work on as many systems as possible and on 32- and 64-bit systems (and on ???-bit systems in the future?). Will the size of a 'double' ever change or will it always be 8 bytes?
I've tried this and it doesn't work...the compiler complains about "invalid operands to binary" because I'm trying bitwise shiftw on a non-integer.
which definitly is not the same number. I guess somewhere in the convertion from double to char* ("<<") something is not right and what can i do to save these double numbers in an accurate manner in a file?