CS212 Programming-II for Engineers

1. CS212Programming-IIfor Engineers Spring 2013

3. Course Material • Syllabus and other course information available at: • dforeman.cs.binghamton.edu/~foreman • Makefiles: • http://www.gnu.org/software/make/manual/make.html • http://www.cprogramming.com/tutorial/makefiles.html

4. Some rules for CS212 • This is primarily a course in Data Structures! • principles are language independent • We will be using C and C++ • Platforms • Lab: Linux • Cygwin is NOT acceptable • Programs submitted must compile using the GNU compiler: G++ • Review makefiles. See links on previous page.

5. Some Course Goals • Use common organizations of data in RAM • Learn to evaluate efficiency • memory space (RAM) needed for storage • algorithms to manipulate the data • Learn to define, implement and use • Structured data types • Basic Abstract Data Types (ADTs) • Learn to use libraries of data structures • STL, Java Collection classes

6. ANSI C++ Compilers • GNU compiler • open source software from the Free Software Foundation • www.gnu.org • available on Bingsuns & labs in LNG103 • built-in on most Linux systems • Cygwin is a Linux-likeenvironment (including the GNU compiler) for Windows (sources.redhat.com/cygwin/) – UNACCEPTABLE!! • Microsoft Visual Studio • integrated editor, compiler, linker, project manager (IDE) • installed on all Computer Center PCs and in Watson Microlab • free to students in Watson courses through the Microsoft Academic Alliance (see Prof. Foreman's website for link)

7. Development Process • Java is an interpreted language • C & C++ are compiled languages Source code Myprog.cpp Source code Myprog.java Interpreter Compiler byte-code file Myprog.class Object Code file Myprog.o Executable file Myprog.exe CPU MUSThave interpreter to run Java pgm CPU

8. Data + Algorithms = Programs • Every program processes data • Data is stored in memory (RAM) at run-time • Java, C, C++ are strongly typed languages • all data items have a type associated with them • Data to be processed must be declared as data objects (variables) using this syntax (for C, C+++ & Java): type name; type name = value; • Type of a data object determines • Allowable operations (+ - * / etc.) • how data is represented in memory (integer, float, etc.)

9. Program structure – pt 1 -preprocessor directives (control compilation) (include header files} -global declarations (constants and types only!) -function prototypes (names & parameters only) myProg.c or myProg.cpp main f1 function definitions (implementations) .... fn

10. compile / link / execute Myprog.cpp Yourprog.cpp #include “myinfo.h” #include “myinfo.h” object's methods Myprog.oYourprog.o Ourpgm.exe (a.out is a default name)

11. Linux Compiler Commands • g++ -c Myprog.cpp • produces Myprog.o • g++ -c Yourprog.cpp • produces Yourprog.o compile only • g++ -o OurpgmMyprog.oYourprog.o • produces Ourpgm link • ./Ourpgm • executes the program execute compile & link • g++ Myprog.cpp • produces a.out

12. Types • Pre-defined (built-in) types • scalar (atomic) types – store a single value • int • char • float, double • bool • structured types – store a collection of values • Most languages have libraries of types • STL for C++ • Java library • Programmer-defined types • create new "types" appropriate for your problem • built from pre-defined types

13. Types - 2 • An int is 8, 16, 32 or 64 bits • defined at compile time • Size of float/double depends on machine arch. • A char is USUALLY 8 bits • Has a numeric value 0-255 • Represents a printable symbol • Some embedded systems may have 16 bit char's • Arithmetic with a char is invalid (e.g.; char+char) • A bool is a single T/F value – • stored as a whole byte(?) - Compiler defined

14. typedef • Allows using the name of an element as a datatype • Does NOT reserve space for the element!!! • Uses no memory

15. Types - 3 • uint8_t is a typedef for unsigned char • Why use it? • Indicates intent – you will do math with it. • Char is printable data in range 32-126 (decimal) • 0-31 and 127-255 are for other uses • but all 256 values are legal • Examples: unsigned char i, x='a', y=0x01; i=x+y; // unclear uint8_t x='a', y=0x01; i=x+y // is clear. (both output 'b' as the value of i)

16. istream ostream iostream ifstream ofstream fstream string vector deque C++ Standard Library classes list stack queue priority_queue map multimap set multiset bitset valarray C++ Types Composite Types Structured Types Scalar Types array struct union class Arithmetic void pointer bool complex Integral Floating point (reals) Characters float double long double Enumerations Integers int shortint long int unsigned short unsigned long unsigned char unsigned char signed char

17. C vs. C++ • C++ is a superset of C • allows ALL of C syntax • adds NEW syntax for • objects • I/O • namespaces • Any C program is a valid C++ program • even if it does not use any of the ++ syntax • compiler knows by the file extension • c vs. cpp

18. namespaces (C & C++) • "namespaces" allow you to assign portions of your program to different namespaces • variable names are local so they may be reused in a program as long as the uses are in different namespaces using namespace std; • the namespace “std” is a little special • you don’t have to specify the “.h” for all standard #includes • e.g.; #include <iostream>#include <iomanip>

19. Structured data types – C arrays • One name for a collection of items • Subscripted (as in standard math notation) • X3 is represented as X[3] • There are no subscript keys on a keyboard! • Multiple values • X[0], X[1], etc. • All elements are same type • Max # elements must be a constant (in C, C++, Java)(for non-dynamic arrays) int x[20]; float y[2012];

20. Arrays - 2 int X[5]; x[3]=17; X[0] X[1] X[2] X[3] X[4] X[0]

21. Arrays - 3 • C does not have an "array" data type • C uses a simple variable with subscript notation: int x[5]; //BUT • max subscript value in definition must be a constant • int x[y]; // is ILLEGAL, even if y has a fixed value • all arrays start at element 0 • above is x[0] … x[4] • C allows multi-dimensioned arrays (like Xijk) int y[3][4][2]; y[0][2][1]=17;

22. Arrays - 4 • compiler ALWAYS reserves memory for the ENTIRE array, whether it is used or not • arrays may be ANY data type, including structs • no protection on accessing beyond real size int x[5]; x[5]=3; // ERROR at RUNTIME compiler might not detect it!!!!! the array has 5 items, numbered 0-4 int j; scanf("enter j%i",j); x[j]=3; compiler CANNOT detect it!!!!!

23. Structured data types - more • "struct" – a simple collection of items • "union" – multiple types for the same RAM bytes • union {char a,b,c,d; int X;} • "a" is the leftmost byte of "X" • "class" – data + functions that operate on it • this is in C++,later in course • All allow collections of dissimilar types

24. struct's • A way to combine basic elements • Create collections of elements • Treat them separately AND/OR as a collection • Use them to create more complex elements • Complex numbers • Real part • Imaginary part

25. struct's – an example structComplx {float my_real_part; float my_imag_part; }; // note the semicolon!!!!! Complx c;// "c" now refers to BOTH parts c.my_real_part=5.2; c.my_imag_part=3.6; // this is equivalent to 5.2+3.6j

26. Pointers • a pointer is a memory address (points to some data) • lets you refer to data without the data's name int x[5] ; // this takes up 20 bytes 5*(4 bytes/int) int *z; // z is a pointer to an int and is 4 bytes int(*y)[5]; // uses only 4 bytes y is a pointer to an array of 5 ints y=&x; // y now points at X (≠ X) z=&x[3]; // z now points to x[3] (has x's address) // z does not EQUAL the value in X[3] int *P[8]; // array of 8 "pointers to int's" (8*4bytes)NOT the integers themselves!!!!!!

27. Dynamic allocation • Often need to make space at runtime • Size/amount of data not pre-defined • Data may need to be ordered by some rule (e.g.; "<") Complx * p; // defines ONLY the POINTER, p // p "points" to a Complex data type p=new Complx; //reserves RAM, p points to it p->my_real_part=3.5; p->my_imag_part=5.6; // equivalent to 3.5+5.6j

28. Abstract Data Types (ADTs) • Collection of data items + operations for it • Independent of programming language • 2 parts: • Definition – of data and operations allowed • Implementation – how data is stored and algorithms to carry out the operations • User – • uses the ADT to solve a problem; • doesn't need to know the implementation details • Needs to know the syntax rules for the ADT

29. The Basic Concept Operations (methods) An ADT encapsulates data and the operations on that data. The data can be accessed only via the operations & operators. data

30. ADT vs. Class • ADT: a model of data AND its related functions • C++ Class: a syntactical & programmatic element for describing how the functions and data are related • An ADT implementation has several parts: • interface function-names (methods) • operators (possibly re-defined symbols) • data • Any/all of these may be public or private

31. ADTs - example structComplx {float my_real_part; float my_imag_part; }; // note the semicolon!!!!! • All elements "visible"

32. C++ console I/O • #include <iostream> • basic operators • << the "insertion" operator • >> the "extraction" operator • stream names for standard I/O • cin is the input "file" • cout is the output "file" • usage • cin>>x; // get a value • cout<<x; // output a value

33. Operators • Ordinary variables have basic operators built-in + - * / % | & || && • New objects (structs, classes) may need more • How do you "add" 2 complex numbers? • Given: complex#'s a and b; • what does a+b mean??? • compiler knows nothing about complex #'s • Define a NEW action (function) to perform "+" • add the real parts, add the imaginary parts • store each result in the proper answer-part.

34. Example – Declare the functions struct Complx {float my_real_part, my_imag_part; }; // below are member functions (i.e.; "methods") floatComplx_get_real(return my_real_part); // not shown floatComplx_init(set my_real_part); // not shown ComplxComplx_add(add 2 complexes); // not shown // orange: declare the structure, green: use it, red: return-value

35. Example- implementation // no automatic functions for initialization Complx x; Complx_init(Complx *x, float a, float b) {x.my_real_part=a; x.my_imag_part=b; } ComplxComplx_add (Complxa, Complx b) {Complxtmp; // need a place for output tmp.my_real_part= a.my_real_part+ b.my_real_part; tmp.my_imag_part= a.my_imag_part + b.my_imag_part; return tmp; } // orange: declarethe structure, green: use it, red: return-value

36. Example-pt 2 void main() { Complx A, B, C; init_Complx (*A,2,2); init_Complx (*B,1,1); C=Complx_add(A,B); printf("C=%d+%dj",C.myreal_part, C.my_imag_part); }

37. Program structure – 2 • Usually, put the struct definition in a header file • #include it later in BOTH : • the implementation file • where the methods are defined • the user-program file • where methods get used