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