CS212 Programming-II for Engineers Spring

Chapter Topic addenda 1 Basic Data Elements & Numeric arrays 2 More ADTs & functions, Intro to Complexity 3 Linear list structures & recursion 1.Queues (using arrays) 2.Linked lists a.Stacks & Queues with pointers b.Prefix, postfix & infix notations 4 General Lists & Strings 5 & 6 Searching, binary trees & Big O again class slides only 1.C++ classes, objects, methods & "friends" 2.I/O, iostream, etc. 7 Sorting 8 Hashing 9 Trees (general) Encoding & Compression (Huffman) 11 Graphs (time permitting) 2

Course Material Syllabus and other course information available at: – dforeman.cs.binghamton.edu/~foreman Makefiles: al/make.html al/make.html akefiles.html akefiles.html 3

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.

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 5

ANSI C++ Compilers GNU compiler – open source software from the Free Software Foundation – – available on Bingsuns & labs in LNG103 – built-in on most Linux systems – Cygwin is a Linux-like environment (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) 6

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

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.) 8

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

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

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

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 12

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 – 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 13

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

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 (decimal) – 0-31 and 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) 15

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

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 17

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 #include

Structured data types – C arrays One name for a collection of items Subscripted (as in standard math notation) – X 3 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]; 19

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

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 X ijk ) int y[3][4][2]; y[0][2][1]=17; 21

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!!!!! 22

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 23

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 24

struct's – an example struct Complx {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 j 25

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!!!!!! 26

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 j 27

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 28

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

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 30

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

C++ console I/O #include 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 32

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. 33

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

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; } Complx Complx_add (Complx a, Complx b) {Complx tmp; // 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: declare the structure, green: use it, red: return-value 35

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); } 36

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 37