CS 2040 Topics for Spring, 2023

This list may be incomplete; check back before exam

• Note 2: Basic Ruby
  Note 3: [2..Ruby]
  • Procedural, OO programming in Ruby, including attributes and class variables
  • Ruby functions
  • Range, Array, Hash types
  • Ruby type system, open classes
  • map, each operations with blocks
  • Standard input; standard output; redirection with <, >, |
  • Exercise: count number of negative values in a list read from a file that is given as standard input

• Note 5: C++ 101
  • Why C++/similarities and differences from Java
  • Why no static void main?
  • Basic data types of C++, differences from Java
    • Name one type that is built-in to C++ but not Java
    • Is there a basic (non-class) type in Java that is not in C++?
    • What Java types are on the stack and what Java types are on the heap?
    • What C++ types are on the stack and what C++ types are on the heap?
  • Declaring variables using type auto
  • Operations, including sizeof
    • Number of bits in a byte, number of bytes in an (ASCII) character
    • sizeof relationships for built-in types
    • What is sizeof(char)?
    • What are legal values for sizeof(int)?
    • What are legal values for sizeof(double)?
  • Scope and lifetime
    • What is the scope and lifetime of x in class A { protected: static int x; };
  • Memory maps
    • Draw a memory map for double a, *b, **c; b = &a; c = & b; **c = 1.2;
  • Declare identifier before can use it
    • When can an identifier be used before declaration?
  • const
    • Is the following legal? void p(const int &x); p(3);
    • Write a function double that takes a value (of any type) and returns that value added to itself without changing the value. Write a fragment of code applying double to some declared, initialize variable, where the type of the variable is in namespace std.
  • Arrays in C++ vs. Java, allocating array on stack vs. heap
    • Declare and define a variable names that is an array of pointers to std::string values. Allow up to 20 names. Set the first name to your own name, but all of the rest should be nullptr.
    • C & C++ arrays are passed by reference. Use a struct to create an array that is passed by value.
    • Are Java arrays passed by reference or value?
    • Assume you are implementing void dosomething(int nums[]); and write int s = sizeof(nums); in the body. What does this set s to? Is there a way to change the declaration of nums so s gets a different value?
    • Why are arrays not very useful in Java? Why are they more useful in C++?
    • What methods are available for C++ arrays?
  • Declaring, dereferencing pointers
    • Given char *p, knowing the difference between p, *p, and &p
  • Count number of negative values in an array of doubles without using []
  • nullptr
  • Initial value of int xs[100]; (depending on where declared)
  • Floating-point constants: 6.022e23

• Note 6: C++ classes
  • How would you define std::string? (naive implementation with .size, .length, .empty, .clear, +=, ==, [])
  • private vs protected vs public
  • Exercise: implement a simply linked list in C++

• Note 7: Modularity in C++
  • #include, separate compilation
  • declaration vs. definition
  • define a function negatives that takes an array of doubles and returns a count of those less than 0
  • declaration before use rule
  • separating method definitions from class definitions - what does this mean?
  • standards for .h (header) files
  • explaining the steps of compilation, why it matters whether an error is a compiler error vs. a linker error
  • namespace

• Note 8: C++ with class
  • inheritance, abstract types, =delete
  • why have inheritance
  • Given class A and B derived from A, knowing if an A* variable can point to a B* value
  • virtual vs. non-virtual methods, vtable
  • l-value vs. r-value
  • pass-by-reference vs. pass-by-value
  • return by reference
  • pure virtual methods

• Note 9: C++ Templates
  • writing a template function, class
  • example: template function to compute average of an array of numbers - what would be the header, body?
  • template class to store 3 items with .one, .two, and .three
  • duck typing with templates

• Note 10: Overloading/copy/move, STL, strings
  • Rule of 5: what are the items, why they are needed
  • recognize move constructor, explain what it does
  • write copy constructor
  • explain elements of assignment operator
  • describe which operator is used in auto x = a; vs. x = b;.
  • given std::string x;, risk of storing x.c_str() in a variable/object

• Note 11: Streams, formatting
  • passing istream, ostream by reference
  • eof-controlled-loop pattern; why

            while ( ! eof ) { read; process }
    

    is a bad idea
  • purpose of stringstream: convert other data types into strings or from strings
  • using ifstream to read files, ofstream to write

• Note 12: Containers, algorithms
  • list<T>::iterator, list<T>::const_iterator, vector<T>::iterator, vector<T>::const_iterator
  • begin: first element
  • end: just after last element
  • Example: if std::vector<double> nums(100); gives an array of 100 items, begin() returns &nums[0] and end() returns &nums[100]
  • roll of #include <algorithm>; esp sort, reverse, fill
  • arguments to sort, reverse: iterators

• Note 13: C
  • goals
  • differences, similarities to C++
  • compilation units, linker, static, extern
    • Explain what the linker does. Give as much detail as you can, being sure to go beyond "combines object files".
  • Makefiles; capturing dependencies and actions, make command
    • Write a makefile entry for a command doit if doit reads files p and q and generates r
  • printf/scanf to print/read an integer, string, character
  • arrays vs. pointers, computing addresses
  • typedef struct { ... } name;
  • passing structs as parameters
  • C-style strings, strlen, strcpy, strcat, strcmp
  • two-dimensional arrays, computing addresses with 2-d arrays
  • #define, dangers of using #define instead of templates
  • #if ... #else ... #endif
  • what union means

• Note 15: memory in C (& C++), stacks
  • be able to explain how stack is managed: what is FP, why FP-1 might be first local variable, given a layout how is data stored in that layout (including with pointers)
  • memory layout: text, rodata, data, bss, heap, stack
  • using malloc and free

• Note 16: Types
  • three definitions of a type
  • How static, dynamic types work: what has to be done at runtime for dynamic types, compile time for static types
  • advantages, disadvantages of int8_t, int16_t, etc.
  • what void* means, how used in C
  • differences between C and C++ type systems
  • casting using (type)
  • Ada and type equivalence rule based on names
  • Dangers of Ada's name equivalence type system
  • strongly typed: same results on all machines independent of representations
  • what it means to create a function pointer, how it is useful in C