C++11 - Initializer lists

In previous version of C++ standard (C++03) we was able to do following array elements assignment:
But we have not been able to do similar assignments to vector:
In order to assign above three elements to vector we had to invoke push_back() method three times:
C++11 present feature which help with above inconvenience. This feature can be achieved thanks to initializer_list template. In C++11, vector implementation has assignment operator taking initializer_list template as parameter:
Thanks to that we can use following assignments to vector:
The same way we can overload assignement operator of any of own class, as well as constructor or any function. Such definition can can take initializer_list template as parameter. Then we will be able to pass initialization list having syntax:

{ element1, element2, element3,...}

as parameter of such function.
Of course STL vector container has implemented constructor having initializer_list as parameter, too. So you can also initialize vector that way:
Having that knowledge and understanding two previously described new features of C++11:
- range-based for loop
- auto type
We can simplify following code written in C++03:
to following quick and simplified form in C++11:
Comfortable, more readable and time saving, right? I agree.

Comments

C++ Multithreading - Race conditions

In the previous C++ Multithreading article I presented you how to pass parameters between threads. Take a detail look on the output of that example once again: In the first line of that output you can notice that output text from two threads is mixed. You are probably wondering why it happens? It is because we are not protecting resources which are shared by two threads (in this example cout stream is shared in both threads) which causes multithreading's phenomenon called race condition . Because threads switching and accessing to shared resources are managed by operating system we do not know when std::cout stream will be accessed by main thread and when it will be accessed by second thread. Therefore in the previous article I mentioned that output of the example can be little different on your computer than my output example. What's more it is possible that this output will be different for few consecutive invoking of the example on the same machine. It is beca...

Advanced C++ - Stack unwinding

Stack unwinding is normally a concept of removing function entries from call stack (also known as Execution stack, Control stack, Function stack or Run-time stack). Call Stack is a stack data structure that stores active functions' addresses and helps in supporting function call/return mechanism. Every time when a function is called, an entry is made into Call stack which contains the return address of the calling function where the control needs to return after the execution of called function. This entry is called by various names like stack frame , activation frame or activation record. With respect to exception handling , stack Unwinding is a process of linearly searching function call stack to reach exception handler. When an exception occurs, if it is not handled in current function where it is thrown, the function Call Stack is unwound until the control reaches try block and then passes to catch block at the end of try block to handle exception. Also, in this proc...

Advanced C++ - Template Functions

Template function are special types of C++ function which can be used with different types (generic types). Thanks to that we can create one body of function which can be used for many different types. When we are creating template function compiler does not define any function for use at that time. Generation of funciton basing on templates are done during compilation process basing of differnt usage of template class. For better understanding take a look on following example: Output of this example is: In point I, we are defining template function which should return sum of two parameters. Without templates we need to define such function separately for each type which we should use it with (ex. separate function for int type, separate for double , separate for any other type). Thanks to template we can generate body of that function only once (as in point I) and use it to any type which is able to use body of that function. In our example we can use this template for an...

Developer Adventure

Search This Blog