Friday, December 08, 2006

“Experience is something you don't get until just after you

need it.”

- Olivier

Numeric data types

Declarations and Initialization

double dx ;

dx=3.5 ;

OR

double dx=3.5 ;

Declarations and Initialization//(comma separated)

double a, b, c=5.6, d ;

double r1,

r2,

r3; //(white spaces ignored)

/*All declarations and statements must end with semicolon ; */

int big=980000;

short small;

cout<<"big="<<big<<endl;

small=big; //don't do this

cout<<"small="<<small<<endl;

int big=980000;short small;cout<<"big="<<big<<endl;small=big; //don't do thiscout<<"small="<<small<<endl;

big=980000small=-3040

short small = 980000;

cout << small << endl;

-3040

Character Data Each character corresponds to a binary code Most commonly use binary codes are ASCII (American

Standard Code for Information Interchange)Character ASCII Code Integer Equivalent

% 0100101 37

3 0110011 51

A 1000001 65

a 1100001 97

b 1100010 98

c 1100011 99

Arithmetic Operators

Addition + Subtraction - Multiplication * Division / Modulus %

Arithmetic Operators

Addition + Subtraction - Multiplication * Division / Modulus %

Modulus returns remainder of division between two integers

% cannot be used on float or double

Example

5 % 2 evaluates to ?

10 % 2 evaluates to ?

Example

5 % 2 evaluates to 1

10 % 2 evaluates to 0

Arithmetic Operators

Division between two integers results in an integer.

The result is truncated, not rounded

Modulo operation17 / 5 evaluates to

17 % 5 evaluates to

Modulo operation17 / 5 evaluates to 3.

17 % 5 evaluates to 2.

Example:

5/3 evaluates to ?

3/6 evaluates to ?

Example:

5/3 evaluates to 1

3/6 evaluates to 0

Priority of Operators1 Parentheses Inner most first

2 Unary operators Right to left(+ -)

3 Binary operatorsLeft to right(* / %)

4 Binary operatorsLeft to right(+ -)

Precedence

Order of mathematical operations is important.Examples:

(3+2)*4 = 5*4 = 20

3+(2*4) = 3 + 8 = 11 * and / evaluated before + and -

Example: 3+2*4 evaluated as 3+(2*4)

Precedence If precedence is equal, then evaluate from left to

right.Examples:

3+2+5 = 5 + 5 = 10

3*2/5 = 6/5 = 1 Parentheses enforce evaluation order

Example: (3+2)*4 = 5*4 = 20

Unary operators: +, - Unary operators: +, -

-3, +17 allowed

Example: 4*(-3) = -12

Assignment Operators

= assignment operator Compound Assignment Operators

operator example equivalent statement += x+=2; x=x+2;

-= x-=2; x=x-2;

*= x*=y; x=x*y;

/= x/=y; x=x/y;

Example x = 4; x *= 5;

Example x = 4; x *= 5; // x = 20

Arithmetic Operators

unary operators• auto increment ++

– post increment x++;– pre increment ++x;

• auto decrement - -– post decrement x- -;– pre decrement - -x;

x++ is executed after it is used x = 7; y = x++; ++x is also equivalent to x = x+1

++x executed before it is used x = 7; y = ++x; --x is equivalent to x = x-1 -- works just like ++, but with subtraction instead of addition

x++ is executed after it is used x = 7; y = x++; // x = 8, y = 7++x is also equivalent to x = x+1

++x executed before it is used x = 7; y = ++x; // x = 8, y = 8--x is equivalent to x = x-1

-- works just like ++, but with subtraction instead of addition

Shortcuts n++

equivalent to n = n + 1read as "add 1 to n"

n-- equivalent to n = n - 1read as "subtract 1 from n"

s += n equivalent to s = s + n read as "add n to s"

s -= n equivalent to s = s - nread as "subtract n from s