Maximum Width of a Printed Double in C++ -

-

I was wondering, how many times would the number of characters be printed in double by using fprintf? My guess is wrong.

Thanks in advance.

Who knows the standard does not say how many points of accuracy a double Provide other than to say (3.9.1.8) "Provides at least the exact form of float," so that you actually how many characters you have to sprintf An arbitrary value will be required even if you know how much your implementation provides, yet there is a question of exponential formatting and so on.

But here's a big question why would you care for the cat? I'm guessing because you are trying to write something like this: 

  double d = ...; Int MAGIC_NUMBER = ...; Four buffer [MAGIC_NUMBER]; Sprintoff (buffer, "% f", d);

There is a bad way to do it, okay because you do not know that the bigger MAGIC_NUMBER should be. You can choose something that should be bigger than 14 or 128k, but then the number you choose is arbitrary, not based on anything but estimates it will be quite big. The number is like MAGIC_NUMBER , not surprisingly, is called. Stay away from them they cry one day.

Instead, there are many ways to do this string formatting without taking care of the buffer size, precision points, so that you can meet with the business, the stream of programming is one: 

  #include & lt; Sstream & gt; Double d = ...; Stringstream ss; SS & lt; & Lt; D; String s = ss.str (); Cout & lt; & Lt; S;

... The second is: 

  #include & lt; Boost \ format \ format.hpp & gt; Double d = ...; String S = (boost :: format ("% 1%")% d) .str (); Cout & lt; & Lt; S;

Comments

Post a Comment

Popular posts from this blog

windows - Heroku throws SQLITE3 Read only exception -

-
After I deploy the app to Heroku, I have to run migration scripts and get this error message ... ITES \ padrino \ prophetmargin & gt; Heroku Rack AR: Rack mutated! SQLite3 :: ReadOnlyException: only one try to write database to read: CREATE TABLE "schema_migrations" ( "version" varchar (255) NOT NULL) /disk1/home/slugs/215264_925fd2c_65a3/mnt/.bundle/gems/gems/ padrino-core- is 0.9.11 / lib / padrino-core / cli / rake.rb: 9: in `init ' how can this be? I also tried to run Heroku dbpush SQLite: //db/my-db.db and that did not work Horoku sqlite3 but using postgres does not do. I'm not sure why you are receiving this error, however, as I have used sqlite3 in development and when pushing it into its travel, they do some magic which migrates to postgrads. I'm absolutely sure how Heroku does 'backwash' this database but it seems that this is happening to you because it's the SQLite db file which is obviously due to Heroku's
Read more

lex - Building a lexical Analyzer in Java -

-
I am currently learning lexical analysis in compiler design. To know how a lexical analyzer actually works, I am trying to build myself. I am planning to make it in Java The input to the lexical analyzer is a .tex file that is of the following format. \ section {script} {intro} \ section {Scope} arbitrary text \ section {relevance} uncontrolled text \ subdivision (profit) arbitrary text \ subsubsection {in real life} \ subdivision {Ingredient} \ end {document} The output of the lecture may be a table of contents with a page number in another file. 1 Introduction 1 1.1 Scope 1 1.2 Relevance 2 1.2.1 Benefits 2 1.2.1.1 Real life 2 1.2.2 loss 3 I hope that This problem is within the scope of Language Analysis Read the .exe file and check '\' and continue to check whether it is actually on search In the sectioning command is set to indicate whether or not a flag variable is the type of sectioning. I hope the above approach will work for the construction of Lexa
Read more

python - rename keys in a dictionary -

-
I want to change the names of keys in a dictionary which are ints, and I need them so that the inputs with key zero They can sort correctly. For example, my keys are like this: '1', '101', '11' and I may need them: '001', '101', '011' What is doing, but I know that there is a better way tmpDict = {} in the ADC for the old: t MpDict ['% 04d'% int (olden)] = addict [oldkey] New controlled = tmpDict You are going wrong about this if you want to draw entries on a line in a specific way, then you have to sort on the extraction. for sorted (D, key = int): print '% s:% R'% (k, d [k]) < / Div>
Read more