narek - Page 3 - Developer IT

STL iterators - advantages

- by Narek

What advantages have STL iterators? Why programmers created that notion?

How does the stream manipulators work?

It is well known that the user can define stream manipulators like this: ostream& tab(ostream & output) { return output<< '\t'; } And this can be used in main() like this: cout<<'a'<<tab<<'b'<<'c'<<endl; Please explain me how does this all work? If operator<< assumes as a second parameter a pointer to the function that takes and returns ostream &, then please explain my why it is necessary? What would be wrong if the function does not take and return ostream & but it was void instead of ostream &? Also it is interesting why “dec”, “hex” manipulators take effect until I don’t change between them, but user defined manipulators should be always used in order to take effect for each streaming?

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How to know if the argument that is passed to the function is a class, union or enum in c++?

- by Narek

I want to define an operator<< for all enums, to cout the value and print that it is an enum like this: code: enum AnyEnum{A,B,C}; AnyEnum enm = A; cout << enm <<endl; output: This is an enum which has a value equal to 0 I know a way of doing this with Boost library by using is_enum struct. But I don’t understand how it works. So that's why, in general, I am interested how to identify if the veriable is a class type, union type or an enum (in compile time).

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Instruction for installing an environment with Eclipse, Qt, and Qt integration with eclipse.

- by Narek

I want to use Qt lib but I don't know how to install Eclipse+Qt+Qtintegration. I have read some forums, that step by step tell what to download, where to download from, and then what to do. But that was for old versions of mentiond products. I ask to Qt developers tell me the way to install these items on Windows. Any forum or site will be fine. Thanks.

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Can we say that virtual function(Polymorphism) is for comfort(ease of handling) as Templates are??

- by Narek

For example concept of Templates in C++ are for comfort as compiler generates some additional code, for your class or for your function, isn't it? So we could live without template by doing some additional (manual work). What about virtual functions??? Are there any situations where both of them are irreplaceable?

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nm utility to get what is defined in .so file returns error

- by Narek

I need to get the symbols defined in .so file. I use latest Mac OS and I do this: /usr/bin/nm -gC libs/armeabi/libhello.so error: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: invalid argument -C Usage: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm [-agnopruUmxjlfAP[s segname sectname] [-] [-t format] [[-arch ] ...] [file ...] As I understand this is another nm utility? It is connected with XCode? How to fix this issue?

Developer IT