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• Finding N contiguous zero bits in an integer to the left of the MSB position of another integer

  - by James Morris

  The problem is: given an integer val1 find the position of the highest bit set (Most Significant Bit) then, given a second integer val2 find a contiguous region of unset bits, with the minimum number of zero bits given by width to the left of the position (ie, in the higher bits). Here is the C code for my solution: typedef unsigned int t; unsigned const t_bits = sizeof(t) * CHAR_BIT; _Bool test_fit_within_left_of_msb( unsigned width, t val1, t val2, unsigned* offset_result) { unsigned offbit = 0; unsigned msb = 0; t mask; t b; while(val1 >>= 1) ++msb; while(offbit + width < t_bits - msb) { mask = (((t)1 << width) - 1) << (t_bits - width - offbit); b = val2 & mask; if (!b) { *offset_result = offbit; return true; } if (offbit++) /* this conditional bothers me! */ b <<= offbit - 1; while(b <<= 1) offbit++; } return false; } Aside from faster ways of finding the MSB of the first integer, the commented test for a zero offbit seems a bit extraneous, but necessary to skip the highest bit of type t if it is set. I have also implemented similar algorithms but working to the right of the MSB of the first number, so they don't require this seemingly extra condition. How can I get rid of this extra condition, or even, are there far more optimal solutions? Edit: Some background not strictly required. The offset result is a count of bits from the high bit, not from the low bit as maybe expected. This will be part of a wider algorithm which scans a 2D array for a 2D area of zero bits. Here, for testing, the algorithm has been simplified. val1 represents the first integer which does not have all bits set found in a row of the 2D array. From this the 2D version would scan down which is what val2 represents. Here's some output showing success and failure: t_bits:32 t_high: 10000000000000000000000000000000 ( 2147483648 ) --------- ----------------------------------- *** fit within left of msb test *** ----------------------------------- val1: 00000000000000000000000010000000 ( 128 ) val2: 01000001000100000000100100001001 ( 1091569929 ) msb: 7 offbit:0 + width: 8 = 8 mask: 11111111000000000000000000000000 ( 4278190080 ) b: 01000001000000000000000000000000 ( 1090519040 ) offbit:8 + width: 8 = 16 mask: 00000000111111110000000000000000 ( 16711680 ) b: 00000000000100000000000000000000 ( 1048576 ) offbit:12 + width: 8 = 20 mask: 00000000000011111111000000000000 ( 1044480 ) b: 00000000000000000000000000000000 ( 0 ) offbit:12 iters:10 ***** found room for width:8 at offset: 12 ***** ----------------------------------- *** fit within left of msb test *** ----------------------------------- val1: 00000000000000000000000001000000 ( 64 ) val2: 00010000000000001000010001000001 ( 268469313 ) msb: 6 offbit:0 + width: 13 = 13 mask: 11111111111110000000000000000000 ( 4294443008 ) b: 00010000000000000000000000000000 ( 268435456 ) offbit:4 + width: 13 = 17 mask: 00001111111111111000000000000000 ( 268402688 ) b: 00000000000000001000000000000000 ( 32768 ) ***** mask: 00001111111111111000000000000000 ( 268402688 ) offbit:17 iters:15 ***** no room found for width:13 ***** (iters is the count of iterations of the inner while loop)

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• Coldfusion: insert new line into string

  - by dmr

  I would like to insert a line break into the first space between words in a string variable. Here is my code so far: <cfset myPosition = find(" ", #myVar#)> <cfset lineBreak = Chr(13)&Chr(10)> <cfset myVar = insert(#lineBreak#, #myVar#, #myPosition#)> What am I doing wrong?

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• Removing text within parentheses (parentheses within parentheses prob)

  - by TenJack

  Hi, I am trying to remove text that is within parentheses (along with the parentheses themselves) but am having trouble with the scenario where there are parentheses within parentheses. This is the method I am using (in Ruby): sentence.gsub(/\(.*?\)/, "") and that works fine until I have a sentence such as: "This is (a test (string))" Then the above chokes. Anyone have any idea how to do this? I am completely stumped.

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• how does fgets internally works?

  - by Registered User

  Well it is a basic question but I seem confused enough. #include<stdio.h> int main() { char a[100]; printf("Enter a string\n"); scanf("%s",a); } Basically the above is what I want to achieve. If I enter a string James Bond then I want that to be stored in array a. But the problem is because of presence of a blank space in between only James word is stored. So how can I solve this one. UPDATE After the replies given below I understand fgets() would be a better choice. I want to know internal working of fgets as why is it able to store the string with space where as scanf is not able to do the same.

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• PHP: Combine Two 16-bit Integers into a 32-bit integer

  - by Goro

  Hello, I am trying to combine two integers in my application. By combine I mean stick one byte stream at the end of the other, not concatenate the strings. The two integers are passed from hardware that can't pass a 32 bit value directly, but passes two consecutive 16-bit values separately. Thanks,

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• Scaling larger Image problem.

  - by krishna

  Hi, I m developing flex application, in which I want to Draw Image from User local hard-drive to the canvas of size 640x360. User can choose Image of bigger resolution & is scaled to Canvas size. But if user selected images of larger resolution like 3000x2000, the scaling take lot time & freezes the application until scale done. Is there any method to scale image faster or kind of threading can be done? I am using matrix to scale Image as below: var mat:Matrix = new Matrix(); var scalex:Number = canvasScreen.width/content.width; var scaley:Number = canvasScreen.height/content.height; mat.scale(scalex,scaley); canvasScreen.graphics.clear(); canvasScreen.graphics.beginBitmapFill(content.bitmapData,mat);

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• Getting the Leftmost Bit

  - by James

  I have a 5 bit integer that I'm working with. Is there a native function in Objective-C that will let me know which bit is the leftmost? i.e. I have 01001, it would return 8 or the position. Thanks

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• How do you tell if two wildcards overlap?

  - by Tom Ritter

  Given two strings with * wildcards, I would like to know if a string could be created that would match both. For example, these two are a simple case of overlap: Hello*World Hel* But so are all of these: *.csv reports*.csv reportsdump.csv Is there an algorithm published for doing this? Or perhaps a utility function in Windows or a library I might be able to call or copy?

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• Android: grab a piece of an ImageView

  - by komidore64

  I have an ImageView from which I want to copy a piece of it in the shape of a circle that I can then re-display to the user at a larger than original size to simulate a zoom effect. Would I use bitmaps for that? Thanks.

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• Faster way to split a string and count characters using R?

  - by chrisamiller

  I'm looking for a faster way to calculate GC content for DNA strings read in from a FASTA file. This boils down to taking a string and counting the number of times that the letter 'G' or 'C' appears. I also want to specify the range of characters to consider. I have a working function that is fairly slow, and it's causing a bottleneck in my code. It looks like this: ## ## count the number of GCs in the characters between start and stop ## gcCount <- function(line, st, sp){ chars = strsplit(as.character(line),"")[[1]] numGC = 0 for(j in st:sp){ ##nested ifs faster than an OR (|) construction if(chars[[j]] == "g"){ numGC <- numGC + 1 }else if(chars[[j]] == "G"){ numGC <- numGC + 1 }else if(chars[[j]] == "c"){ numGC <- numGC + 1 }else if(chars[[j]] == "C"){ numGC <- numGC + 1 } } return(numGC) } Running Rprof gives me the following output: > a = "GCCCAAAATTTTCCGGatttaagcagacataaattcgagg" > Rprof(filename="Rprof.out") > for(i in 1:500000){gcCount(a,1,40)}; > Rprof(NULL) > summaryRprof(filename="Rprof.out") self.time self.pct total.time total.pct "gcCount" 77.36 76.8 100.74 100.0 "==" 18.30 18.2 18.30 18.2 "strsplit" 3.58 3.6 3.64 3.6 "+" 1.14 1.1 1.14 1.1 ":" 0.30 0.3 0.30 0.3 "as.logical" 0.04 0.0 0.04 0.0 "as.character" 0.02 0.0 0.02 0.0 $by.total total.time total.pct self.time self.pct "gcCount" 100.74 100.0 77.36 76.8 "==" 18.30 18.2 18.30 18.2 "strsplit" 3.64 3.6 3.58 3.6 "+" 1.14 1.1 1.14 1.1 ":" 0.30 0.3 0.30 0.3 "as.logical" 0.04 0.0 0.04 0.0 "as.character" 0.02 0.0 0.02 0.0 $sampling.time [1] 100.74 Any advice for making this code faster?

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• How to find about structure of bitmap and JPEG files?

  - by Sorush Rabiee

  I'm trying to write a very simple image processing program for fun and practice. I was using System.Drawing. ... .Bitmap class to handle images and edit their data. but now I want to write my own class of Bitmap object implementation and want to know how bmp files (and other common bitmap formats) and their meta-data (indexing, color system & etc) are stored in files, and how to read and write them directly?

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• Repeated regular expression

  - by javaguy

  How can I parse a strings like : name1="val1" name2="val2" name3="val3" I cannot use split(\s+) as it can be name = "val 1". I am doing java but any laguage is okay.

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• Python, add trailing slash to directory string, os independently

  - by Horace Ho

  How can I add a trailing slash (/ for *nix, \ for win32) to a directory string, if the tailing slash is not already there? Thanks!

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• String concatenation in C

  - by Mechko

  if I want to construct a const char * out of several primitive type arguments, is there a way to build the string using a similar to the printf?

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• How do I do high quality scaling of a image?

  - by pbhogan

  I'm writing some code to scale a 32 bit RGBA image in C/C++. I have written a few attempts that have been somewhat successful, but they're slow and most importantly the quality of the sized image is not acceptable. I compared the same image scaled by OpenGL (i.e. my video card) and my routine and it's miles apart in quality. I've Google Code Searched, scoured source trees of anything I thought would shed some light (SDL, Allegro, wxWidgets, CxImage, GD, ImageMagick, etc.) but usually their code is either convoluted and scattered all over the place or riddled with assembler and little or no comments. I've also read multiple articles on Wikipedia and elsewhere, and I'm just not finding a clear explanation of what I need. I understand the basic concepts of interpolation and sampling, but I'm struggling to get the algorithm right. I do NOT want to rely on an external library for one routine and have to convert to their image format and back. Besides, I'd like to know how to do it myself anyway. :) I have seen a similar question asked on stack overflow before, but it wasn't really answered in this way, but I'm hoping there's someone out there who can help nudge me in the right direction. Maybe point me to some articles or pseudo code... anything to help me learn and do. Here's what I'm looking for: 1. No assembler (I'm writing very portable code for multiple processor types). 2. No dependencies on external libraries. 3. I am primarily concerned with scaling DOWN, but will also need to write a scale up routine later. 4. Quality of the result and clarity of the algorithm is most important (I can optimize it later). My routine essentially takes the following form: DrawScaled( uint32 *src, uint32 *dst, src_x, src_y, src_w, src_h, dst_x, dst_y, dst_w, dst_h ); Thanks! UPDATE: To clarify, I need something more advanced than a box resample for downscaling which blurs the image too much. I suspect what I want is some kind of bicubic (or other) filter that is somewhat the reverse to a bicubic upscaling algorithm (i.e. each destination pixel is computed from all contributing source pixels combined with a weighting algorithm that keeps things sharp. EXAMPLE: Here's an example of what I'm getting from the wxWidgets BoxResample algorithm vs. what I want on a 256x256 bitmap scaled to 55x55. And finally: the original 256x256 image

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• How do I count the number of occurrences of a char in a String?

  - by Bart

  I have the string a.b.c.d I want to count the occurrences of '.' in an idiomatic way, preferably a one-liner. (Previously I had expressed this constraint as "without a loop", in case you're wondering why everyone's trying to answer without using a loop).

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• Remove first and last characters from a string in Lisp

  - by powerj1984

  I am passing in command line arguments to my Lisp program and they are formatted like this when they hit my main function: ("1 1 1" "dot" "2 2 2") I have a dot function and would like to call it directly from the argument, but first I must strip the " characters. I tried variations of this function: (defun remove-quotes (s) (setf (aref s 0) '"")) to no avail, Lisp complains that "" is not a member of base-char. Thanks!

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• In Javascript is there a function that returns the number of times that a given string occurs?

  - by William Calleja

  In Javascript is there a function that returns the number of times that a given string occurs? I need to return a numeric value that is equal to the number of times that a given string occurs within a particular string for instance: var myString = "This is a test text" If I had to search for 'te' in the above string it would return 2.

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• How to cut a string variable into more?

  - by DanSogaard

  So I've a string: string x = "DR\nDC\nDD"; I want to get each line in a separated variable like this: string y1 = "DR"; String y2 = "DC"; String y3 = "DD"; How can I do that?.

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• How to convert Java Image into JPEG array of bytes?

  - by unknownthreat

  Is there a way to convert a Java Image, encode it into JPEG (but not saving it to a file), and store it as an array of bytes? (byte[]) I need the JPEG-encoded image as an array of bytes.

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• Filling pattern changes with object's position. Java.

  - by Gabriel A. Zorrilla

  I created a bufferedimage which i applied to a Rectangle to use as filling pattern to shape S. If i change S's position, the filling pattern changes with it instead of remaining "fixed". What could it be? Image: (the pattern is a 3 stripes, all with the same aspect ratio) :

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• increasing string size through loop

  - by calccrypto

  what's a simple way to increase the length of a string given an arbitrary integer x? like 'a' goes to 'z' and then goes to 'aa' to 'zz' to 'aaa', etc.

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• C++ Check Substring of a String

  - by user69514

  I'm trying to check whether or not the second argument in my program is a substring of the first argument. The problem is that it only work if the substring starts with the same letter of the string. .i.e Michigan - Mich (this works) Michigan - Mi (this works) Michigan - igan (this doesn't work) #include <stdio.h> #include <string.h> #include <string> using namespace std; bool my_strstr( string str, string sub ) { bool flag = true; int startPosition = -1; char subStart = str.at(0); char strStart; //find starting position for(int i=0; i<str.length(); i++){ if(str.at(i) == subStart){ startPosition = i; break; } } for(int i=0; i<sub.size(); i++){ if(sub.at(i) != str.at(startPosition)){ flag = false; break; } startPosition++; } return flag; } int main(int argc, char **argv){ if (argc != 3) { printf ("Usage: check <string one> <string two>\n"); } string str1 = argv[1]; string str2 = argv[2]; bool result = my_strstr(str1, str2); if(result == 1){ printf("%s is a substring of %s\n", argv[2], argv[1]); } else{ printf("%s is not a substring of %s\n", argv[2], argv[1]); } return 0; }

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• Efficient way in Python to add an element to a comma-separated string

  - by ensnare

  I'm looking for the most efficient way to add an element to a comma-separated string while maintaining alphabetical order for the words: For example: string = 'Apples, Bananas, Grapes, Oranges' addition = 'Cherries' result = 'Apples, Bananas, Cherries, Grapes, Oranges' Also, a way to do this but while maintaining IDs: string = '1:Apples, 4:Bananas, 6:Grapes, 23:Oranges' addition = '62:Cherries' result = '1:Apples, 4:Bananas, 62:Cherries, 6:Grapes, 23:Oranges' Sample code is greatly appreciated. Thank you so much.

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• PHP - Resize an image and fill gaps of proportions with a color

  - by Kerry

  I am uploading logos to my system, and they need to fix in a 60x60 pixel box. I have all the code to resize it proportionately, and that's not a problem. My 454x292px image becomes 60x38. The thing is, I need the picture to be 60x60, meaning I want to pad the top and bottom with white each (I can fill the rectangle with the color). The theory is I create a white rectangle, 60x60, then I copy the image and resize it to 60x38 and put it in my white rectangle, starting 11px from the top (which adds up to the 22px of total padding that I need. I would post my code but it's decently long, though I can if requested. Does anyone know how to do this or can you point me to code/tutorial that does this?

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