Department of Electrical and Computer Engineering Introduction to C++: Primitive Data Types, Libraries and Operations By Hector M Lugo-Cordero August 27, 2008

The Department of Electrical and Computer Engineering 2 History In the beginning no programming languages existed. –5 + 2 : Programming Languages appeared: –A language that both computers and humans understand. –Able to write instructions to make the computer make some actions.

The Department of Electrical and Computer Engineering 3 History (cont.) Low level programming (Assembly) –Reads and write directly on the hardware. –Each line is equivalent to a binary code :  add 5, 2 –Needs always to have registers in the instrucion mov ax, 5 add ax, 2 High level programming –Tries to get closer to the human language. –Each line is equivalent to one or more binary codes. int x = 5 + 2;

The Department of Electrical and Computer Engineering 4 History (cont.) High Level Programming Paradigms –Functional Breaks problems into sub problems Each problem is solved by a function/method/subroutine Examples: –FORTRAN (Formula Translator): first language that allowed algebraic notation –Cobol –C

The Department of Electrical and Computer Engineering 5 History (cont.) High Level Programming Paradigms (cont.) –Object Oriented The problem can be written in objects Each object (noun) has its attributes (adjectives) and methods (verbs) (e.g. Person) Examples: –C++ (compiler translates into machine language (binary code)) –Java (runs with JVM) –C# (runs with.net framework) Note that all these are imperative languages (use of variables to control program flow)

The Department of Electrical and Computer Engineering 6 Outline Variables and Data types –Numeric –Char –Boolean Modifiers Libraries –iostream –cstdio –cstdlib –cmath –cstring Operations –Arithmetic –Logic

The Department of Electrical and Computer Engineering 7 Variables and Data Types Variable: just like in math a variable is something that stores information and changes its value if desired. –Type –Name –Memory Allocation (will be covered later) –e.g. int x = 5;

The Department of Electrical and Computer Engineering 8 Variables and Data Types (cont.) Name –Can not start with numbers –Can not contain white spaces –Typical notation Constant values are stored with names in capital Two words may be written with _ or now with the Java notation (first letter is capital) Names should describe the function of the variable –e.g. int age = 25; //The age of a person is 25 You may start a comment with //comment or /* comment */ for multiple lines All instructions end with a ; (for now )

The Department of Electrical and Computer Engineering 9 Variables and Data Types (cont.) Types –Numeric short/long/int: represents integer numbers float/double: represents real numbers –char: stores a single alphanumeric character Has an ASCII value e.g. char letter = ‘A’; int ascii = letter; //ascii = 65 –bool: can be either true or false. Use for making decisions (C must import #include ) In C/C++ every non-zero number is taken as true while zero is taken as a false. –void: has no value (will be used later in pointers)

The Department of Electrical and Computer Engineering 10 Variables and Data Types (cont.) Types –string: contains a character sequence also known in C as char* (char pointer). Need to import #include –time: represents time values Need to import #include –FILE*: data type use to read/write files (will be discussed later)

The Department of Electrical and Computer Engineering 11 Modifiers unsigned: uses numbers with no sign (positive values only). As a consequence the range is extended. const: used to defined constant variables extern: –Keyword that tells the compiler that the variable or function is defined in another file. –Also may be use to specify the compiler to be used.

The Department of Electrical and Computer Engineering 12 Libraries iostream –cout –cin –cerr –clog cstdio –Contains file handling functions –We will discuss this in full detail later

The Department of Electrical and Computer Engineering 13 Libraries (cont.) cstdlib –Contains memory management –System calls –Random functions (srand/rand) –Conversion funcions atof: converts a string to double atoi: converts a string to integer atol: converts a string to long

The Department of Electrical and Computer Engineering 14 Libraries (cont.) cmath –Contains math functions cos, sin, tan acos, asin, atan exp, log, log10 pow, sqrt ceil, floor, fabs –We can define PI and other constants with #define PI … #define EXP …

The Department of Electrical and Computer Engineering 15 Libraries (cont.) cstring (contains string related functions) –strlen: returns the length of a string int length = strlen(name); –strtok: splits a string into tokens char str[] ="- This, a sample string."; char * pch; printf ("Splitting string \"%s\" into tokens:\n",str); pch = strtok (str,",.-"); while (pch != NULL) { –printf ("%s\n",pch); –pch = strtok (NULL, ",.-"); }

The Department of Electrical and Computer Engineering 16 Operations Add: x + 3 Substract: y – 5 Mutiplication: x * 8.3 Division: –If operands are integers ½ = 0 with reminder of 1 –Remainder can be obtained 1%2 –If operands are real numbers 1.0/2.0 = 0.5

The Department of Electrical and Computer Engineering 17 Operations Shifts: –Left: z << 2; –Right: z >> 3; Logical And: x & 5 Logical Or: y | 2 Logical Not: t = ~t Logical Xor: x ^ y

The Department of Electrical and Computer Engineering 18 Operations Unary increment: ++a, a++ Unary decrement: --a, a— x += 3  x = x + 3 x -= 3  x = x - 3 x *= 3  x = x * 3 x /= 3  x = x / 3 x <<= 3  x = x << 3 x >>= 3  x = x >> 3

The Department of Electrical and Computer Engineering 19 Questions?