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Introduction

  • Goal of C++:

    • Programs almost as efficient as assembler/machine code, but as elegantly abstract as one wishes
    • Stroustrup: “C++ is a language for developing and using elegant and efficient abstractions”

  • C++ is core C++ plus standard library developed in C++

  • Defining a new type is the most fundamental programming activity in C++

    • A well-designed new type differs from a build in type only in the way it is defined, not in the way it is used!
    • Library – a collection of user defined types

Types of Memory

Three fundamental types of memory:

  • Static memory
    • Pre-allocated when program is loaded
      • In global scope ore given with static keyword
  • Stack - in local or statement scope
    • small/cheap
    • deallocated when goes out of scope
  • Dynamic memory (free store)
    • large/more expensive
    • Allocated and deallocated with new and delete operators
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int c_arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
int main()
{
    vector<int> vec = {1, 2, 3, 4, 5, 6, 7, 8, 9};
    vector<int>* vecd = new vector<int>{1, 2, 3, 4, 5, 6, 7, 8};
    ...
      for (auto i : c_arr) cout << i << " ";
    …
      delete vecd;
    return 0;
}

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int main()
{
    static int c_arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    vector<int> vec = {1, 2, 3, 4, 5, 6, 7, 8, 9};
    vector<int>* vecd = new vector<int>{1, 2, 3, 4, 5, 6, 7, 8};
    ...
      for (auto i : c_arr) cout << i << " ";
    …
      delete vecd;
    return 0;
}

Pointers and References

  • A pointer * can point to any object in memory or have a special value nullptr
    • Typed or void*
    • If typed, defines pointer arithmetic and can be dereferenced
  • In C, function parameters are passed by value, but pointers can be used
  • C++ reference &
    • A different name for an object, must be initialized

C Arrays

  • Indexed from 0 to n-1
  • A name of the array is a (constant) pointer to the first element
    • a[j]==*(&a[0] + j) == *(a + j)
Last update: June 10, 2021