CHAPTER THREE SUMMARY



Variables



-a variable is a named memory location which stores a value

--to use a variable in a program, it must be defined by giving it a type and identifier



eg: double Radius



Once defined the variable must be given a value



eg: Radius = 12.3 ;



the = sign is similar to the := in Pascal which means that the value is assigned to the variable



CIN -- used for input: see previous notes



Using Named Constants



-defined in a statement and begins with the word "const"



--this is used to define a constant: in math Pi is a constant value (3.14159)...to represent this in C++, you do the following:



const double PI = 3.14 ;





--a constant is used to represent a value that does not change during the execution of a program







Choosing Identifiers



Rules for choosing identifiers:



Built in Data Types



1. double

2. int and long

3. char:

Example: char Ch:

Ch = 'A';

cout<

displays : A





VARIABLE DEFINITIONS



VARIABLES can be defined in single statements or in multiple variables in one line



example: int x,y,z

Char ch1,ch2



Expressions and Operators



-built in arithmetic operations include: (*) multiplication,

(+) addition, (-) subtraction, and ( / ) division



Promotion: numeric values of various types can be mixed in an expression: an expression involving two doubles, results in a double, however, whenever an integer and a double are used, C++ promotes the value with the narrow range to the value with the wider range: integer becomes a double: this avoids the problem known in Pascal as "type mismatch"



Integer Division: if you divide two integers, the resulting number will be truncated, or the decimals will be cut off!



Type Casting: when real division is done, type casting converts one of the values into a real number



Modulus Division: represented by %, Modulus division returns the remainder....similar to MOD in Pascal



Operator Precedence: same as order of operations in mathematics







Output Formatting