Chapter 2: Basic Elements of C++
The
Basics of a C++ Program
•Function: collection of statements; when
executed, accomplishes something
−May
be predefined or standard
•Syntax: rules that specify which statements
(instructions) are legal
•Programming
language: a set of rules, symbols, and special
words
•Semantic
rule: meaning of the instruction
Comments
•Comments are for the reader, not the
compiler
•Two types:
−Single
line
// This is a C++ program. It prints
the sentence:
−Multiple
line
/*
You can include comments that can
occupy several lines.
*/
example :
#include <iostream>
using namespace std;
void main ()
{
//Cout<< "AL_Wessam";
cout<<"alwessam";
/*
cout << "a";
cout << "b";
cout << "c";
*/
}
Output after Run (alwessam)
Special
Symbols
+ ?
- ,
* <=
/ !=
. ==
; >=
•Reserved words, keywords, or word symbols
−Include:
•int
•float
•double
•char
•const
•void
•return
Identifiers
•Consist of letters, digits, and the
underscore character (_)
•Must begin with a letter or underscore
•C++ is case sensitive
−NUMBER is not the same as number
•Two predefined identifiers are cout and cin
•Unlike reserved words, predefined
identifiers may be redefined, but it is not a good idea
The following are legal identifiers in
C++:
−first
−conversion
−payRate
Whitespaces
•Every C++ program contains whitespaces
−Include
blanks, tabs, and newline characters
•Used to separate special symbols,
reserved words, and identifiers
•Proper utilization of whitespaces is
important
−Can
be used to make the program readable
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