teaching machines

CS 330 Lecture 21 – First C++

March 26, 2012 by Chris Johnson. Filed under cs330, lectures, spring 2012.

Agenda

• what do you know about C++?
• C++ roots: Simula
• Bjarne Strostroup
• TIOBE index for C++
• values vs. pointers vs. references (which?)
• classes in C++
• mapping between C with Classes and C
• can be made on stack
• for heap, why new/delete? (RAII)
• access control
• constructor/deconstructor
• use initialization lists
• default constructor
• copy constructor
• an example class: FasterString
• Bjarne’s goal in C++: type parity
• custom classes on stack or heap, unlike Simula
• can overload builtin operators to work with classes

TODO

• Have a peek through the C++ FAQ.

Code

FasterString.cpp

class FasterString {
  public:
    FasterString();
    FasterString(const char *src);

    const char *GetCString();

  private:
    char *characters;
    int length;
};

FasterString::FasterString() :
  characters(NULL),
  length(0) {
}

FasterString::FasterString(const char *src) :
  length(strlen(src)),
  characters(NULL) {
  /* characters = malloc(sizeof(char) * length); */
  characters = new char[length];
  memcpy(characters, src, length * sizeof(char));
}

const char *FasterString::GetCString() {
  return characters;  
}

int main() {
  FasterString f("hi, jeff");
  // ctor has already been called, and f is valid
  std::cout << "f.GetCString(): " << f.GetCString() << std::endl;
  return 0;
}

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