Determining output (printing) of float with %f in C/C++ -

-

I have gone through the earlier discussions on temporary point numbers but it did not clear my problem , I knew this floating point issue could be normal in every forum but my question is not related to floating point arithmetic or comparison. I'm curious about its representation and output% F.

The question is straight forward: "How to determine the exact output: 

  float = & lt; some_value & gt; F; printf ("% f \ n", & lt; float_valable & gt;);

lets us consider this code snippet: 

  Float f = 43.2f, f1 = 23.7f, f2 = 58.89f, f3 = 0.7f; Printf ("f1 =% f \ n", f); printf ("f2 =% f \ n", f1); Printf ("f3 =% f \ n", f2); printf ("f4 =% f \ N", f3);

Output: 

  f1 = 43.200001 f2 = 23.700001 f3 = 58.889999 F 4 = 0.700000

I know that% f (for double) is a default preci of 6 Sai also I know that the problem Or (in this case) can be fixed using double but I'm curious about the output f2 = 23.700001 and f3 = 58.889999 .

Edit: I know that the floating point number can not be displayed properly, but what is the rule of obtaining the nearest representable value?

IPEE 754 is talking about float, which has 24 binary accuracy. Points: Represent the number in binary (of course) and make the number round for the 24th most important digit. The result will be the nearest floating point.

For example, 23.7 representation in binary 

  10111.1011001100110011001100110011 ...

after the rounding You will get 

  10111.1011001100110011010

that is in decimal 

  23.700000762939453125

After roaming in the sixth decimal place, you will have 

  23.700001

which is actually your printf .


Comments

Post a Comment

Popular posts from this blog

c# - How to capture HTTP packet with SharpPcap -

-
I would like to capture all incoming HTTP packets on my machine. To do this, I am using SharpPcap which is a WinPcap The cover is. SharpPcap works very well, but it captures TCP packets and what it wants to do for me is a very low level. Does anyone know how can I easily get full HTTP requests / reactions from all these TCP packets? Thanks SharpPcap is already able to capture the packet in the same way That's what the virus does (just in the code instead of the GUI). And you can either either parse them directly or you can put them in the drive in the common .pcap file format. The steps to parse the capture are: Open a connection at any time Loop a while Or start capturing using an event callback Parsing the raw packet for the type you want If you are reading .PPP dump files In addition to calling you an offline capture reader is almost the same, there is no need to select an interface, and you can set the majority There is no need to do the modes. All st...
Read more

php - Multiple Select with Explode: only returns the word "Array" -

-
By using Wordpress I have created a multiple selection box so that users can select categories to exclude. When the page is initially loaded, I see my predefined default option. However, when I select a new value and I save ... I only see the word "Array" and have not chosen anything else? & lt; Class = "amultiple" id = "& lt; php echo $ value ['id'] ;? gt;" name = "& gt; php echo $ value ['id'] ;; gt; []" Multiple = "multiple" size = "8" & gt; & Lt ;? Php global option; Foreign currency ($ value as value $) {if (get_settings ($ value ['id']) === FALSE {$$ value ['id'] = $ value ['std']; } And {$$ value ['id'] = get_settings ($ value ['id']); }} $ Ranges = & amp; Amp; Categories ('type = post & orderbiz = name & amp; hide_empty = 1'); If ($ ranges) {$ ex_cat = implode (',', $ tt_cat_exclude); Forex Currency ($ range a...
Read more

php - jQuery AJAX Post not working -

-
I do not understand why this script does not work. It has something to do within AJAX PostScript / Function. Right now, when I submit my form, it runs php code on the same page. What it should do, send the values ​​of the form for Project_Azax.fp, then there will be a refund of success on the page which is correct or false. $ (document) .ready (function () {$ ('div # didIt'). Hide (); $ ('form [name = adminForm]'). Submit (function () ($ {'.post' ('/ project_ajax.php', {action: $ ('[name = action]') Val (), pId: $ ('[name = pId]'). Val (), name ('[Name = name]'. Val (), url: $ ('[url = url]'). Val (), summary: ('[summary = summary]'). Val ()}, Function (data) {if (data.success) {$ ('div # didIt') .Sliddown ('slow');} and {warning ('unsuccessful SA!');}}, 'Jason'); return false ;});}); What is the code for project_ajax.php below ... if ($ _ POST ['action'] == ...
Read more