C++ Notes

direct_initialization.cpp

int a = 0;
// In C++ there is copy initialization
int b = a;
// And direct initialization
int c(0);

// They are not the same, and have different behavior.  People tend to favor
// copy initialization, except for direct initialization in a few cases.
// See this SO answer http://stackoverflow.com/a/4293816

empty.cpp

// Calling a function directly followed by <> causes the template(generic) to use the default
// type definitions for arguments
newTaskScheduled.wait_until<>(lock, taskQueue.begin()->first)

// http://stackoverflow.com/a/20398693

initialization.cpp

/*  
  Use the area after the colon of a constructor to:
  1. Calling base class constructors
  2. Initialising member variables before the body of the constructor executes
  
  See here for more details: http://stackoverflow.com/a/2785639 
*/

// Example:
CScheduler::CScheduler() : nThreadsServicingQueue(0), stopRequested(false), stopWhenEmpty(false) {

}

// Note: the syntax for modifying member variables in the initialization list is like calling a function. This was something
// that was confusing for me at first.
// More can be found here http://www.cprogramming.com/tutorial/initialization-lists-c++.html.

notes.cpp

// A double colon is used when accessing static members of classes/namespaces
class A {
  public:
    static void StaticFunction() { }
    void NonStaticFunction() { }

    int variable;
};

int main() {
  StaticFunction();  // this is an error, because 'StaticFunction' doesn't exist in the global namespace 
  A::StaticFunction();  // this is OK, because now the compiler knows to look in the A class to find StaticFunction.

  // in order to call non-static functions or to access variables, we need an object
  A obj;  // 'obj' is our object

  obj.variable = 5;  // here we use the . operator because we have an object.  No need for the :: operator
   // because the scope is implied by the object type ('obj' is an 'A', so it knows to look in 'A' for 'variable')

  obj.NonStaticFunction();  // same thing with member function calls
}

// So in conclusion, use :: when accessing a member from a static class, use . when accessing a member
// from an object

pre_directives.cpp

// You can use pre-processor directives to replace sections of the code
#define TABLE_SIZE 100
int table1[TABLE_SIZE];
int table2[TABLE_SIZE];

// Turns into
int table1[100];
int table2[100];

// #ifdef & #ifndef adds or discards sections of the code