1. Foundations of Computer Science C & C++ programming lecture 2
CS 2308
Foundations of Computer Science C & C++ programming
lecture 2

2. Outline history of C++ development of C C++ - better C
essential computer terms
hardware terms
software terms
C++ program layout, first program

3. Where did C++ come from?
BCPL (Basic Combined Programming Language) was developed in 1967 as a language for writing operating systems and software compilers
In 1970, the creators of 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 of operating systems (one of the largest and most complicated pieces of software) is written in C or C++
source code for Microsoft Windows Vista contains 50 million lines of mostly C/C++ code
source code Red Hat Linux v.7.1 contains 30 million lines of C/C++ code

4. The Birth of C++
C++ is an extension of C developed by Bjarne Stroustrup in 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 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!

5. Hardware 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

6. Hardware computer contains 5 main components
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

7. Software
operating system - allocates computer resources, launches other programs and makes sure they work properly
Program - 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

8. Software
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

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

10. A First Program - Greeting.cpp
// Program: Display greetings
// Author(s): Ima Programmer
// Date: 1/25/1999
#include <iostream>
int main() {
cout << "Hello,world!" << endl; }
Preprocessor
directive
Comments
Function named main() indicates start of program
output
statement

11. Special Characters Character Name Meaning // Double slash
Beginning of a comment #
Pound sign
Beginning of preprocessor directive
< >
Open/close brackets
Enclose filename in #include
( )
Open/close parentheses
Used when naming a function
{ }
Open/close brace
Encloses a group of statements
" "
Open/close quotation marks
Encloses string of characters ;
Semicolon
End of a programming statement