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  • Subplots of multidimensional arrays in Matlab

    - by altes4ia
    I have a 10x10x10 array, z. How do I plot everything in the SAME window so that I would have the 3 plots for z(:,:,1) and below it the three plots for z(:,:,2) etc ? This is what I have so far: for i = 1:10 z=z(:,:,i); figure(i) subplot(1,2,1) surf(z) %code, obtain new array called "new1"... subplot(1,2,2) surf(new1) %code, obtain new array called "new2"... subplot(1,3,3) surf(new2) end;

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  • C question: Padding bits in unsigned integers and bitwise operations (C89)

    - by Anonymous Question Guy
    I have a lot of code that performs bitwise operations on unsigned integers. I wrote my code with the assumption that those operations were on integers of fixed width without any padding bits. For example an array of 32 bit unsigned integers of which all 32 bits available for each integer. I'm looking to make my code more portable and I'm focused on making sure I'm C89 compliant (in this case). One of the issues that I've come across is possible padded integers. Take this extreme example, taken from the GMP manual: However on Cray vector systems it may be noted that short and int are always stored in 8 bytes (and with sizeof indicating that) but use only 32 or 46 bits. The nails feature can account for this, by passing for instance 8*sizeof(int)-INT_BIT. I've also read about this type of padding in other places. I actually read of a post on SO last night (forgive me, I don't have the link and I'm going to cite something similar from memory) where if you have, say, a double with 60 usable bits the other 4 could be used for padding and those padding bits could serve some internal purpose so they cannot be modified. So let's say for example my code is compiled on a platform where an unsigned int type is sized at 4 bytes, each byte being 8 bits, however the most significant 2 bits are padding bits. Would UINT_MAX in that case be 0x3FFFFFFF (1073741823) ? #include <stdio.h> #include <stdlib.h> /* padding bits represented by underscores */ int main( int argc, char **argv ) { unsigned int a = 0x2AAAAAAA; /* __101010101010101010101010101010 */ unsigned int b = 0x15555555; /* __010101010101010101010101010101 */ unsigned int c = a ^ b; /* ?? __111111111111111111111111111111 */ unsigned int d = c << 5; /* ?? __111111111111111111111111100000 */ unsigned int e = d >> 5; /* ?? __000001111111111111111111111111 */ printf( "a: %X\nb: %X\nc: %X\nd: %X\ne: %X\n", a, b, c, d, e ); return 0; } is it safe to XOR two integers with padding bits? wouldn't I XOR whatever the padding bits are? I can't find this behavior covered in C89. furthermore is the c var guaranteed to be 0x3FFFFFFF or if for example the two padding bits were both on in a or b would c be 0xFFFFFFFF ? same question with d and e. am i manipulating the padding bits by shifting? I would expect to see this below, assuming 32 bits with the 2 most significant bits used for padding, but I want to know if something like this is guaranteed: a: 2AAAAAAA b: 15555555 c: 3FFFFFFF d: 3FFFFFE0 e: 01FFFFFF Also are padding bits always the most significant bits or could they be the least significant bits? Thanks guys EDIT 12/19/2010 5PM EST: Christoph has answered my question. Thanks! I had also asked (above) whether padding bits are always the most significant bits. This is cited in the rationale for the C99 standard, and the answer is no. I am playing it safe and assuming the same for C89. Here is specifically what the C99 rationale says for §6.2.6.2 (Representation of Integer Types): Padding bits are user-accessible in an unsigned integer type. For example, suppose a machine uses a pair of 16-bit shorts (each with its own sign bit) to make up a 32-bit int and the sign bit of the lower short is ignored when used in this 32-bit int. Then, as a 32-bit signed int, there is a padding bit (in the middle of the 32 bits) that is ignored in determining the value of the 32-bit signed int. But, if this 32-bit item is treated as a 32-bit unsigned int, then that padding bit is visible to the user’s program. The C committee was told that there is a machine that works this way, and that is one reason that padding bits were added to C99. Footnotes 44 and 45 mention that parity bits might be padding bits. The committee does not know of any machines with user-accessible parity bits within an integer. Therefore, the committee is not aware of any machines that treat parity bits as padding bits. EDIT 12/28/2010 3PM EST: I found an interesting discussion on comp.lang.c from a few months ago. Bitwise Operator Effects on Padding Bits (VelocityReviews reader) Bitwise Operator Effects on Padding Bits (Google Groups alternate link) One point made by Dietmar which I found interesting: Let's note that padding bits are not necessary for the existence of trap representations; combinations of value bits which do not represent a value of the object type would also do.

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  • Economical way to get many harddrives into rack mount?

    - by Industrial
    Hi everyone, Please bear with me as being a bit of a newcomer at 19" rack-mounted equipment. I've thought a fair bit lately about the best way of getting 4x or 6x of 2.5" hard drives into my rack and are right now currently slightly confused about would be the best (economical) solution. After scouting the market, I've found this type of disk array units that offers built in RAID and a lot of drive slots and a truckload of geek cred, but at a price that just isn't going to fit in my budget. I've also found these type of cute adapters that takes two 2.5" drives in one 3.5" slot, but I will obviously need a chassie with a lot of 3.5" spaces in order to make it work. So what is the most economical way to house my harddrives in my rack?

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  • How do I make these inputs relate to each other?

    - by dmanexe
    I have a series of checkbox inputs and corresponding text area inputs to allow specification of quantity. Here's what the two fields look like when the item is static (i.e. only 1): <input type="checkbox" name="measure[checked][]" value="<?=$item->id?>"> <input type="hidden" name="measure[quantity][]" value="1" /> Here's what the input fields look like for all items that have a specifiable quantity: <input type="checkbox" name="measure[checked][]" value="<?=$item->id?>"> <input class="item_mult" value="0" type="text" name="measure[quantity][]" /> This would play nicely, if within the array, it didn't output like this, after collecting it with: $field = $this->input->post('measure',true); Array ( [quantity] => Array ( [0] => 1 [1] => 1 [2] => 1 [3] => 1 [4] => 1 [5] => 1 [6] => 25 [7] => 0 [8] => 0 [9] => 0 [10] => 1 [11] => 1 [12] => 1 [13] => 1 [14] => 1 [15] => 1 [16] => 1 [17] => 1 [18] => 1 [19] => 1 [20] => 1 [21] => 1 [22] => 0 [23] => 0 [24] => 0 [25] => 0 [26] => 0 [27] => 0 [28] => 0 [29] => 0 [30] => 0 [31] => 0 [32] => 0 [33] => 0 [34] => 0 [35] => 0 [36] => 0 [37] => 0 [38] => 0 [39] => 0 [40] => 0 [41] => 1 [42] => 1 [43] => 1 [44] => 1 [45] => 1 [46] => 1 [47] => 1 [48] => 1 [49] => 1 [50] => 1 [51] => 1 [52] => 0 [53] => 0 [54] => 0 ) [checked] => Array ( [0] => 4 [1] => 6 [2] => 13 ) ) I understand what the values in the checked array are, I just do not understand how to relate the first field to the second, later in the program. How do I incorporate the correct code to relate checked items to quantities?

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  • rotating bitmaps. In code.

    - by Marco van de Voort
    Is there a faster way to rotate a large bitmap by 90 or 270 degrees than simply doing a nested loop with inverted coordinates? The bitmaps are 8bpp and typically 2048*2400*8bpp Currently I do this by simply copying with argument inversion, roughly (pseudo code: for x = 0 to 2048-1 for y = 0 to 2048-1 dest[x][y]=src[y][x]; (In reality I do it with pointers, for a bit more speed, but that is roughly the same magnitude) GDI is quite slow with large images, and GPU load/store times for textures (GF7 cards) are in the same magnitude as the current CPU time. Any tips, pointers? An in-place algorithm would even be better, but speed is more important than being in-place. Target is Delphi, but it is more an algorithmic question. SSE(2) vectorization no problem, it is a big enough problem for me to code it in assembler Duplicates How do you rotate a two dimensional array?. Follow up to Nils' answer Image 2048x2700 - 2700x2048 Compiler Turbo Explorer 2006 with optimization on. Windows: Power scheme set to "Always on". (important!!!!) Machine: Core2 6600 (2.4 GHz) time with old routine: 32ms (step 1) time with stepsize 8 : 12ms time with stepsize 16 : 10ms time with stepsize 32+ : 9ms Meanwhile I also tested on a Athlon 64 X2 (5200+ iirc), and the speed up there was slightly more than a factor four (80 to 19 ms). The speed up is well worth it, thanks. Maybe that during the summer months I'll torture myself with a SSE(2) version. However I already thought about how to tackle that, and I think I'll run out of SSE2 registers for an straight implementation: for n:=0 to 7 do begin load r0, <source+n*rowsize> shift byte from r0 into r1 shift byte from r0 into r2 .. shift byte from r0 into r8 end; store r1, <target> store r2, <target+1*<rowsize> .. store r8, <target+7*<rowsize> So 8x8 needs 9 registers, but 32-bits SSE only has 8. Anyway that is something for the summer months :-) Note that the pointer thing is something that I do out of instinct, but it could be there is actually something to it, if your dimensions are not hardcoded, the compiler can't turn the mul into a shift. While muls an sich are cheap nowadays, they also generate more register pressure afaik. The code (validated by subtracting result from the "naieve" rotate1 implementation): const stepsize = 32; procedure rotatealign(Source: tbw8image; Target:tbw8image); var stepsx,stepsy,restx,resty : Integer; RowPitchSource, RowPitchTarget : Integer; pSource, pTarget,ps1,ps2 : pchar; x,y,i,j: integer; rpstep : integer; begin RowPitchSource := source.RowPitch; // bytes to jump to next line. Can be negative (includes alignment) RowPitchTarget := target.RowPitch; rpstep:=RowPitchTarget*stepsize; stepsx:=source.ImageWidth div stepsize; stepsy:=source.ImageHeight div stepsize; // check if mod 16=0 here for both dimensions, if so -> SSE2. for y := 0 to stepsy - 1 do begin psource:=source.GetImagePointer(0,y*stepsize); // gets pointer to pixel x,y ptarget:=Target.GetImagePointer(target.imagewidth-(y+1)*stepsize,0); for x := 0 to stepsx - 1 do begin for i := 0 to stepsize - 1 do begin ps1:=@psource[rowpitchsource*i]; // ( 0,i) ps2:=@ptarget[stepsize-1-i]; // (maxx-i,0); for j := 0 to stepsize - 1 do begin ps2[0]:=ps1[j]; inc(ps2,RowPitchTarget); end; end; inc(psource,stepsize); inc(ptarget,rpstep); end; end; // 3 more areas to do, with dimensions // - stepsy*stepsize * restx // right most column of restx width // - stepsx*stepsize * resty // bottom row with resty height // - restx*resty // bottom-right rectangle. restx:=source.ImageWidth mod stepsize; // typically zero because width is // typically 1024 or 2048 resty:=source.Imageheight mod stepsize; if restx>0 then begin // one loop less, since we know this fits in one line of "blocks" psource:=source.GetImagePointer(source.ImageWidth-restx,0); // gets pointer to pixel x,y ptarget:=Target.GetImagePointer(Target.imagewidth-stepsize,Target.imageheight-restx); for y := 0 to stepsy - 1 do begin for i := 0 to stepsize - 1 do begin ps1:=@psource[rowpitchsource*i]; // ( 0,i) ps2:=@ptarget[stepsize-1-i]; // (maxx-i,0); for j := 0 to restx - 1 do begin ps2[0]:=ps1[j]; inc(ps2,RowPitchTarget); end; end; inc(psource,stepsize*RowPitchSource); dec(ptarget,stepsize); end; end; if resty>0 then begin // one loop less, since we know this fits in one line of "blocks" psource:=source.GetImagePointer(0,source.ImageHeight-resty); // gets pointer to pixel x,y ptarget:=Target.GetImagePointer(0,0); for x := 0 to stepsx - 1 do begin for i := 0 to resty- 1 do begin ps1:=@psource[rowpitchsource*i]; // ( 0,i) ps2:=@ptarget[resty-1-i]; // (maxx-i,0); for j := 0 to stepsize - 1 do begin ps2[0]:=ps1[j]; inc(ps2,RowPitchTarget); end; end; inc(psource,stepsize); inc(ptarget,rpstep); end; end; if (resty>0) and (restx>0) then begin // another loop less, since only one block psource:=source.GetImagePointer(source.ImageWidth-restx,source.ImageHeight-resty); // gets pointer to pixel x,y ptarget:=Target.GetImagePointer(0,target.ImageHeight-restx); for i := 0 to resty- 1 do begin ps1:=@psource[rowpitchsource*i]; // ( 0,i) ps2:=@ptarget[resty-1-i]; // (maxx-i,0); for j := 0 to restx - 1 do begin ps2[0]:=ps1[j]; inc(ps2,RowPitchTarget); end; end; end; end;

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  • Using Array Variables For FILE_GET_CONTENTS

    - by Whoshooter
    I have a script all done now and everything has been debugged and it works, except for the last hurdle. This script grabs pertinent information on bank web sites, takes that data and uses it to populate a template and then it's all posted to Wordpress - BUT I get an error because the file_get_contents function fails taking each url from the Array. I've var_dumped the array and all the URLS are there in the [0] key, so this is what I tried. master data is the scraped URL source the script uses urlscrape_array is the collection of URLS $master_data = file_get_contents($urlscrape_array[0]); When I run the script using a URL like below it works beautifully every time; $master_data = file_get_contents("http://www.somesite/somepage.html"); This is the error I get when I try to use the first example' Warning: file_get_contents() expects parameter 1 to be string, array given in /home3/path/public_html/mysite.com/boise_project/scriptmainpage.php on line 13 As requested here is a sample of the var_dump on $urlscrape_array[0] array(504) { [0]=> string(56) "http://www.somepage.com/somepage-3178.html" [1]=> string(54) "http://www.somepage.com/somepage-16.html" [2]=> string(56) "http://www.somepage.com/somepage-3202.html" [3]=> string(56) "http://www.somepage.com/somepage-4324.html" [4]=> string(56) "http://www.somepage.com/somepage-4777.html" [5]=> string(56) "http://www.somepage.com/somepage-5140.html" [6]=> string(56) "http://www.somepage.com/somepage-5220.html" [7]=> string(56) "http://www.somepage.com/somepage-9205.html" [8]=> string(56) "http://www.somepage.com/somepage-3251.html" [9]=> string(56) "http://www.somepage.com/somepage-3323.html" [10]=> string(56) "http://www.somepage.com/some-page-3797.html" [11]=> string(56) "http://www.somepage.com/some-page-4145.html" [12]=> string(56) "http://www.somepage.com/some-page-3191.html" [13]=> string(55) "http://www.somepage.com/some-page-329.html" [14]=> string(56) etc.... Error as per the foreach statement provided by Uptown Warning: Invalid argument supplied for foreach() in /home3/bettyt45/public_html/bdbud.com/boise_project/boise-wordpress.php on line 12 NULL print_r resulst below; Array ( [0] => Array ( [0] => http://www.somesite.com/some-page-3178.html [1] => http://www.somesite.com/some-page-16.html [2] => http://www.somesite.com/some-page-3202.html [3] => http://www.somesite.com/some-page-4324.html [4] => http://www.somesite.com/some-page-4777.html [5] => http://www.somesite.com/some-page-5140.html [6] => http://www.somesite.com/some-page-5220.html [7] => http://www.somesite.com/some-page-9205.html [8] => http://www.somesite.com/some-page-3251.html [9] => http://www.somesite.com/some-page-3323.html [10] => http://www.somesite.com/some-page-3797.html [11] => http://www.somesite.com/some-page-4145.html [12] => http://www.somesite.com/some-page-3191.html [13] => http://www.somesite.com/some-page-329.html [14] => http://www.somesite.com/some-page-3341.html [15] => http://www.somesite.com/some-page-3758.html [16] => http://www.somesite.com/some-page-4180.html [17] => http://www.somesite.com/some-page-9014.html [18] => http://www.somesite.com/some-page-5987.html [19] => http://www.somesite.com/some-page-1542.html [20] => http://www.somesite.com/some-page-3004.html [21] => http://www.somesite.com/some-page-9034.html [22] => http://www.somesite.com/some-page-3385.html [23] => http://www.somesite.com/some-page-3435.html [24] => http://www.somesite.com/some-page-6389.html [25] => http://www.somesite.com/some-page-6992.html [26] => http://www.somesite.com/some-page-7051.html HERE IS THE CODE I USED TO CREATE THE ARRAY ABOVE; $urlscrape_data = file_get_contents('http://www.bdbud.com/boise_project/boise-urls.htm'); preg_match_all('~http\:\/\/www.creditunionsonline.com\/credit\-union\-\d{1,4}?\.html~', $urlscrape_data, $urlscrape_matches); $urlscrape_array = $urlscrape_matches;

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  • Blackberry Development, adding dynamic number of buttons and setting Fieldchangelistener() for them

    - by Nikesh Yadav
    Hi, I am adding dynamic number of buttons in a Blackberry application and trying to get different events on each button click. I am not able to apply the setchangelistener() for these array of buttons as once the loop finishes after adding all the buttons, the events gets generated only for the last indexed button. If I make us of getIndex(), it runs fine only if I am not adding any other fields on my screen, but if I add other fields along with these array of buttons, the getIndex() function count them in the indexing as well. Can anyone please help me out in setting FieldChangeListener to array of ButtonField? Here is a sample code of the way I am using the array of ButtonField. I the code I have added two test LabelField at the top of the screen, if I remove them the code will run fine and I will get different result for each button click, but if I keep them active, the indexing gets effected and the Button wont work. package buttonclickloop; import net.rim.device.api.ui.DrawStyle; import net.rim.device.api.ui.Field; import net.rim.device.api.ui.FieldChangeListener; import net.rim.device.api.ui.component.ButtonField; import net.rim.device.api.ui.component.LabelField; import net.rim.device.api.ui.container.HorizontalFieldManager; import net.rim.device.api.ui.container.MainScreen; public class ButtoncClickLoop extends MainScreen { int i = 0; private ButtonField[] btn = new ButtonField[50]; public ButtoncClickLoop() { // TODO Auto-generated constructor stub LabelField Field1 = new LabelField("Field1"); LabelField Field2 = new LabelField("Field2",DrawStyle.RIGHT | ButtonField.USE_ALL_WIDTH); HorizontalFieldManager FieldHmgr = new HorizontalFieldManager(); FieldHmgr.add(Field1); FieldHmgr.add(Field2); FieldHmgr.setMargin(0,0,10,5); add(FieldHmgr); while (i < 3){ FieldChangeListener listener = new FieldChangeListener() { public void fieldChanged(Field field, int context) { context = field.getIndex(); if (field == btn[context]){ add(new LabelField("Label" + context + "")); } } }; btn[i] = new ButtonField("Button" + i + ""); btn[i].setChangeListener(listener); add(btn[i]); i = i + 1; } } } Thanks, Nikesh

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  • Java ArrayList initialization

    - by Jonathan
    I am aware that you can initialize an array during instantiation as follows: String[] names = new String[] {"Ryan", "Julie", "Bob"}; Is there a way to do the same thing with an ArrayList? Or must I add the contents individually with array.add()? Thanks, Jonathan

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  • Sorting Numbers ins a Object.

    - by user133611
    Hi I have an NSMutableArray of objects, let's say 'Person' Objects. I want to sort the NSMutable Array by person.savings i.e if suppose person having savings 1000,1050,500,1200,2000,1050 i want the Array in the ascending order. Thank You.

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  • Why is System.arraycopy native in Java?

    - by James B
    I was surprised to see in the Java source that System.arraycopy is a native method. Of course the reason is because it's faster. But what native tricks is the code able to employ that make it faster? Why not just loop over the original array and copy each pointer to the new array - surely this isn't that slow and cumbersome? Thanks, -James

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  • C++ delete[] operator

    - by Betamoo
    Is this the right way to use delete[] operator? int* a=new int[size]; delete[] a; If yes, Who (compiler or GC or whoever) will determine the size of the newly created array? and where will it store the array size? Thanks

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  • Cannot Convert from int[][] to int*

    - by cam
    I have a 3x3 array that I'm trying to create a pointer to and I keep getting this array, what gives? How do I have to define the pointer? I've tried every combination of [] and *. Is it possible to do this? int* pTemp = tempSec;

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  • CakePHP 3-level-deep model associatons

    - by user357452
    Hi, I am relatively new to CakePHP, I am doing fine with the documentation, but I've been trying to find a way out to this problem for weeks and I don't seem to find the solution, I am sure it is easy and maybe even automagicaly doable, but I just don't know how to find it (maybe I don't know the jargon for these kind of things) My model structure is like this: <?php class Trip extends AppModel { var $belongsTo = array( 'User' => array( 'className' => 'User', 'foreignKey' => 'user_id' ), 'Start' => array( 'className' => 'Place', 'foreignKey' => 'start_id' ), 'End' => array( 'className' => 'Place', 'foreignKey' => 'end_id' ), 'Transport' => array( 'className' => 'Transport', 'foreignKey' => 'transport_id' ) ); } ?> <?php class Place extends AppModel { var $belongsTo = array( 'User' => array( 'className' => 'User', 'foreignKey' => 'user_id' ), 'Country' => array( 'className' => 'Country', 'foreignKey' => 'country_id' ), 'State' => array( 'className' => 'State', 'foreignKey' => 'state_id' ), 'City' => array( 'className' => 'City', 'foreignKey' => 'city_id' ) ); var $hasMany = array( 'PlaceStart' => array( 'className' => 'trip', 'foreignKey' => 'start_id', 'dependent' => false ), 'PlaceEnd' => array( 'className' => 'trip', 'foreignKey' => 'end_id', 'dependent' => false ) ); } ?> <?php class State extends AppModel { var $belongsTo = array( 'Country' => array( 'className' => 'Country', 'foreignKey' => 'country_id', 'conditions' => '', 'fields' => '', 'order' => '' ) ); var $hasMany = array( 'City' => array( 'className' => 'City', 'foreignKey' => 'city_id', 'dependent' => false ) ); } ?> ... and so forth with User, City, Country, and Transport Models. What I am trying to achieve is to get all the information of the whole tree when I search for a Trip. <?php class TripController extends AppController { function index() { debug($this->Trip->find('first')); } } Outputs Array ( [Trip] => Array ( [id] => 6 [created] => 2010-05-04 00:23:59 [user_id] => 4 [start_id] => 2 [end_id] => 1 [title] => My trip [transport_id] => 1 ) [User] => Array ( [id] => 4 [name] => John Doe [email] => [email protected] ) [Start] => Array ( [id] => 2 [user_id] => 4 [country_id] => 1 [state_id] => 1 [city_id] => 1 [direccion] => Lincoln Street ) [End] => Array ( [id] => 1 [user_id] => 4 [country_id] => 1 [state_id] => 1 [city_id] => 4 [address] => Fifth Avenue ) [Transport] => Array ( [id] => 1 [name] => car ) ) Here is the question: How do I get in one query all the information down the tree? I would like to have something like Array ( [Trip] => Array ( [id] => 6 [created] => 2010-05-04 00:23:59 [User] => Array ( [id] => 4 [name] => John Doe [email] => [email protected] ) [Start] => Array ( [id] => 2 [user_id] => 4 [Country] => Array ( [id] => 1 [name] = Spain ) [State] => Array ( [id] => 1 [name] = Barcelona ) [City] => Array ( [id] => 1 [name] = La Floresta ) [address] => Lincoln Street ) [End] => (same as Start) [title] => My trip [Transport] => Array ( [id] => 1 [name] => car ) ) ) Can CakePHP create this kind of data? Not only for $this->Model->find() but also for $this->paginate() as for example: // filter by start if(isset($this->passedArgs['start'])) { //debug('isset '.$this->passedArgs['start']); $start = $this->passedArgs['start']; $this->paginate['conditions'][] = array( 'OR' => array( 'Start.address LIKE' => "%$start%", 'Start.State.name LIKE' => "%$start%", 'Start.City.name LIKE' => "%$start%", 'Start.Country.name LIKE' => "%$start%" ) ); $this->data['Search']['start'] = $start; } It seems like a rough question but I am sure this is extensively done and documented, I'd really appreciate any help. Thanks Cheers Naoise

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  • Relational Database arrays (H2, Java)

    - by Daddy Warbox
    I seem to have two options on how to implement arrays, and I want to know which I should go with: Use the ARRAY data type and (from what I understand) effectively serialize data objects into the database (which in my case are just wrapped primitive types; don't know of another way to make this work). Use a separate table and map with foreign keys for each array item. If you have experience with this (especially with H2), which would you recommend?

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  • Help with PHP and associative arrays

    - by errata
    Hello. I have to do a simple calculator in php based on user's input and choice from select field, something like this: <?php $a = $_GET['a']; $b = $_GET['b']; $array = array( "option1" => 0.1, "option2" => 0.15, "option3" => 0.3, "option4" => 3, "option5" => 3, "option6" => 16, "option7" => 16, "option8" => 16 ); echo "<form action='calc.php' method='get'>"; echo "<input type='text' name='a' value='".$a."'> of "; echo "<select name='b'>"; foreach ($array as $k => $v) { echo "<option value='".$v."'>".$k."</option>"; } echo "</select> "; echo "<input type='submit' value='='> "; $total_volume = $a * $b; echo $total_volume; echo "</form>"; ?> Well, for now everything works fine, but the idea is that after user submits form, the page reloads with sent amount in input field and selected option which user actually selected... First thing is easy: I just put value="a" in my input field, but I'm not sure how to make a selected option in <select> field??? I started with this: foreach ($array as $k => $v) { echo "<option value='".$v."'"; if ($b == $v) { echo " selected "; } echo ">".$k."</option>"; } ...but this is obviously not working as expected... Please help me with this easy one :) Thanks!

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  • Which is faster: in_array() or a bunch of expressions in PHP?

    - by Darryl Hein
    Is it faster to do the following: if ($var != 'test1' && $var != 'test2' && $var != 'test3' && $var != 'test4') { ... } Or: if (!in_array($var, array('test1', 'test2', 'test3', 'test4') { ... } Is there a number of values at which point it's faster to do one or the other? (In this case, the array used in the second option doesn't alreay exist.)

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  • PHP checking $_POST

    - by sea_1987
    I have some form fields that when a form is submitted creates an array within the $_POST, I needing to check the this array has atleast 4 keys, how can I check that? I have no idea

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  • Desktop SATA drives in SATA <-> FC array

    - by chris
    Let's assume you've got a box like one of these with space for 24 SATA disks. What are the best bits of advice for deploying this? For instance, should you be greedy and go for the 1.5 or 2tb disks or are they just not reliable enough to be used in an array like this and you should stick with 640gb or 750gb disks instead? Also, I know that FC (or generically, "enterprise class") disks have a different error recovery strategy than desktop disks. An enterprise disk will fail a read quickly and report to the controller that it wasn't able to read that block, and the RAID controller will quickly regenerate the info from the parity disk and mark the block as bad. A desktop disk, on the other hand, will try and try and try again to get the data, and in pathological cases this may cause a raid controller to fail the whole disk because the read operation times out. So there are a couple aspects to this question: What's the best sort of disk to get today? (ie specific disks on the market in Feb 2010) Generically, what should someone look for when trying to buy something like this that kinda walks the line between enterprise and consumer? Lastly -- is there anything that can be done with current "consumer" disks to make them more suitable for array use? IE can you use a SMART configuration to change the error recovery strategy used by the disk? Thanks!

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  • Ubuntu 10.04 - Add RAID 1 Array?

    - by N Rahl
    I have an existing Ubuntu 10.04 desktop system setup and running on a hard drive (Drive A). I'd like to add 2 more hard drives (Drives B & C, same size) to the system and mount them as a RAID 1 array. How do I do that? I know how to create RAID arrays during the installation, but I don't want to reinstall my system, and I shouldn't have to since my system files will stay on their own drive separate from the RAID array. I've physically added both drives to the system, and formatted them as EXT3 with gparted. Ubuntu's disk utility has a "create raid" option, but it won't let me select any of my drives (it thinks they're all full). I don't mind using mdadm, but I've found several guides that are old, and give conflicting advice. Some say I have to edit an /etc/raidtab file, some say this is done automatically. So what's the current (Ubuntu 10.04) preferred way of adding a RAID 1 to an existing system? It should turn into a raid at boot, and mount itself in /home/myname/files/. Thanks!

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  • Removing a device in "removed" state from Linux software RAID array

    - by Sahasranaman MS
    My workstation has two disks(/dev/sd[ab]), both with similar partitioning. /dev/sdb failed, and cat /proc/mdstat stopped showing the second sdb partition. I ran mdadm --fail and mdadm --remove for all partitions from the failed disk on the arrays that use them, although all such commands failed with mdadm: set device faulty failed for /dev/sdb2: No such device mdadm: hot remove failed for /dev/sdb2: No such device or address Then I hot swapped the failed disk, partitioned the new disk and added the partitions to the respective arrays. All arrays got rebuilt properly except one, because in /dev/md2, the failed disk doesn't seem to have been removed from the array properly. Because of this, the new partition keeps getting added as a spare to the partition, and its status remains degraded. Here's what mdadm --detail /dev/md2 shows: [root@ldmohanr ~]# mdadm --detail /dev/md2 /dev/md2: Version : 1.1 Creation Time : Tue Dec 27 22:55:14 2011 Raid Level : raid1 Array Size : 52427708 (50.00 GiB 53.69 GB) Used Dev Size : 52427708 (50.00 GiB 53.69 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Intent Bitmap : Internal Update Time : Fri Nov 23 14:59:56 2012 State : active, degraded Active Devices : 1 Working Devices : 2 Failed Devices : 0 Spare Devices : 1 Name : ldmohanr.net:2 (local to host ldmohanr.net) UUID : 4483f95d:e485207a:b43c9af2:c37c6df1 Events : 5912611 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 1 0 0 1 removed 2 8 18 - spare /dev/sdb2 To remove a disk, mdadm needs a device filename, which was /dev/sdb2 originally, but that no longer refers to device number 1. I need help with removing device number 1 with 'removed' status and making /dev/sdb2 active.

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  • Accessing a vector<vector<int>> as a flat array

    - by user1762276
    For this array: vector<vector<int> > v; v.push_back(vector<int>(0)); v.back().push_back(1); v.back().push_back(2); v.back().push_back(3); v.back().push_back(4); I can output {1, 2, 3, 4} easily enough: cout << v[0][0] << endl; cout << v[0][1] << endl; cout << v[0][2] << endl; cout << v[0][3] << endl; To access it as a flat array I can do this: int* z = (int*)&v[0].front(); cout << z[0] << endl; cout << z[1] << endl; cout << z[2] << endl; cout << z[3] << endl; Now, how do I access the multidimensional vector as a flat multidimensional array? I cannot use the same format as accessing a single-dimensional vector: // This does not work (outputs garbage) int** n = (int**)&v.front(); cout << n[0][0] << endl; cout << n[0][1] << endl; cout << n[0][2] << endl; cout << n[0][3] << endl; The workaround I've found is to do this: int** n = new int* [v.size()]; for (size_t i = 0; i < v.size(); i++) { n[i] = &v.at(i).front(); } cout << n[0][0] << endl; cout << n[0][1] << endl; cout << n[0][2] << endl; cout << n[0][3] << endl; Is there a way to access the entire multidimensional vector like a flat c-style array without having to dynamically allocate each dimension above the data before accessing it? Speed is not critical in the implementation and clarity for maintenance is paramount. A multidimensional vector is just fine for storing the data. However, I want to also expose the data as a flat c-style array in the SDK so that it can be easily accessible by other languages. This means that exposing the vectors as an STL object is a no go. The solution I came up with works fine for my needs as I only evaluate the array once at the very end of processing to "flatten" it. However, is there a better way to go about this? Or am I already doing it the best way I possibly can without re-implementing my own data structure (overkill since my flatten code is only a few lines). Thank you for your advice, friends!

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