CS Computer Science I

BCPL was developed in 1967 as a language for writing operating systems and software compilers In 1970, the creators of the UNIX operating system needed a high-level language that provided enough power and flexibility for their task. They developed B (a derivative of BCPL) In 1972, an enhanced and improved version of the language called C was used to code most of UNIX most operating systems (one of the largest and most complicated pieces of software) are written in C or C++ source code for Microsoft Windows Vista contains 50 million lines of mostly C/C++ code source code of Red Hat Linux v.7.1 contains 30 million lines of C/C++ code Where did C++ come from?

C++ is an extension of C developed by Bjarne Stroustrup in the early 1980s C/C++ are possibly the most popular programming languages in use today C++ absorbed the best features of C and made a few additions to make it even more powerful and convenient to use C was written to combine the ease of high-level language with the power of low-level language –with C it is very easy to write code that is difficult to understand and hard to debug one of the major additions introduced by C++ is the use of OBJECTS. The Birth of C++

program - set of instructions to computer that does something useful. software - collection of programs hardware - physical devices that make up computer equipment computer - PC/mainframes/workstations computer contains 5 main components CPU - follows the instructions and performs calculations specified by the program input device - any device that allows outside world to communicate information to the computer output device - any device that allows computer to communicate information to the outside world main memory/RAM - a list of addressable numbered memory locations that computer can operate upon –bit - the least possible amount of information: 0 or 1 –byte - 8 bits –memory location - single (indivisible) portion of memory that holds data –address - number that identifies a memory location secondary memory - memory that is used for keeping a permanent record of information - disks/data CDs/flash drives Hardware

operating system - allocates computer resources, launches other programs and makes sure they work properly program (again) - set of instructions for computer to follow data - input to the program running/executing program - performing program instructions on given data natural language - language used by humans high-level language - language (close to natural) that is understood by humans, C++ is a high-level language low-level language (assembly) - a list of instructions a computer can follow : add X, Y, Z machine language - list of instructions in binary format a computer understands compiler - a program that translates high-level language into low-level language code - source (high-level language), object (low-level language) library - set of previously developed routines linker - program that takes object code, adds needed routines from libraries and produces executable code executable code - can run on computer Software

include directive - tells compiler where to find certain items about the program main part (main function) - contains instructions for the computer, starts and ends with braces: {} statement - single instruction to computer each statement is ended with a semicolon ; program consists of a sequence of statements comment is a portion of a line ignored by the compiler - serves to make the code easier to understand by humans breaks and indentation is for humans - compiler ignores them. Should make the program easier to read! C++ Program Layout #include int main() { statement 1; // comment statement 2;... }

// displays a greeting // Michael Rothstein // 1/12/2014 #include using namespace std; int main() { cout << "Hello, World!" << endl; } First Program: helloWorld.cpp preprocessor directive output statement comments function named main() indicates start of program

Rules of Programming syntax - the principles of constructing (structuring) the program semantics – the meaning of the program and its parts style – non-syntactic rules of program writing aimed at making a program easier to read and understand