c++ - Extract template type from initializer list -


I have a problem with C ++ 11 templated code. I have a template function 

  Template & lt; Typename T & gt; F (const std :: vector & lt; T & gt; & amp; v) {/ * do something here;}   
 When I call  f (v) , where  v  is  std :: vector & lt; some_type & gt; V; , the program is just fine. However, if I give an initial list on  f  then say  f ({a, b, c}), where  a ,  b < / Code>,  c  are all of the same type, say  some_type , I get a compilation error:  template logic 't' / code>, therefore For example,  f  f . Int & gt; ({A, b, c});  aggregates when  a ,  b  and  c  all  int  s are any standard initializer list There is no way to specify the template type  T  from the  std :: vector & lt; T & gt;  is defined as taking the parameters? Actually I just want to be able to call  f ({initializer_list});  f  without specifying the type of elements of   initializer_list .   
 
 
 You can just define  
  template < typename t & gt; Void f (const std :: initializer_list & lt; t & gt; and v) {f (std :: vector & lt; T & gt; (v)); }   
 To work for this, initializer_list should be of some specific type, hence  f ({0, 1.41421, 2.71828, 3.14159})  will not be Work, but  f ({0.0, 1.41421, 2.71828, 3.14159})  will be.

Comments

Post a Comment

Popular posts from this blog

Java - Error: no suitable method found for add(int, java.lang.String) -

I'm in the middle of homework work and I'm stuck. At this point in my code, I think that I should have a GUI window that opens and allows me to type "inserted text number". Notice is not going anywhere but at this point, If I pass through the problem then it will be in a linked list. I am getting two of the same error for the lines. Add (index, element); And I can not seem to get past it, there is no suitable method for the error "add (int, java. string string)". Code is below, please advise. To clarify - this will not be a method error because it is a linked list. There should not be any way involved. import java.awt. *; Import java.awt.event. *; Import javax.swing. *; Import java.util. *; Import java.util.Scanner; Import java.util.LinkedList; Public class TopTenList JFrame {Private TopTenList tt; See the Private JTextArea list; Private JTextField cmdTextField; Private JTextField resultsTestfield; // This GUI window is the code for the public toptist...
Read more

java - JPA TypedQuery: Parameter value element did not match expected type -

I am using JPA 2.0 and getting the following code in the DAO layer: Public Zero Test () {string key = "status"; String [] Conditions = {"A", "B"}; & Lt; TestTable & gt; Results = Search (Keys, Conditions); } Public listing & lt; TestTable & gt; Search (string key, object value error) {string sql = "test ndf to testlet and jade nand." + Key + "in:" + key; TypedQuery & LT; TestTable & gt; Query = entityManager.createQuery (SQL, TestTable.class); Query.setParameter (key, Arrays.asList (valueArr)) / *** Error Line *** Return query.getResultList (); } In the above error line, it throws the following exception: java.lang.IllegalArgumentException: parameter value element [[Ljava.lang.String; @ cbe5bc] did not match the expected type [java.lang.String] Why is this expected type string while actually this string []? Please help! Note: This is derived from the normal routine and is a simplified code. I can no...
Read more

c++ - static template member variable has internal linkage but is not defined -

Yes, I know, there is a question with almost the same title, but it refers to a different situation. Error message) In my case, I have a .cpp file with a big named designation name (implementation details). There is a property class template with a static data member in that name space, which I need to access from outside the unknown namespace. I give it a little bit of meat: file.hpp namespace Bar {template & lt; Typename A & gt; Struct foo {static_assert (is_same & lt; a, float & gt; :: value} is_same & lt; a, double>: value, ""); Fixed zero set_static_var (a const & x); // ...}; } and file.cpp namespace {template & lt; Typename A & gt; Struct foo_traits {// supports the implementation of several static code bars: foo & lt; & Gt; Fixed A data; }; The template's & lt; & Gt; Float foo_traits & lt; Float & gt; :: datum; // No change if this is in the global namespace template & lt; & Gt; Doub...
Read more