Friday, December 08, 2006 “Experience is something you don't get until just after you need it.”...
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Transcript of Friday, December 08, 2006 “Experience is something you don't get until just after you need it.”...
Friday, December 08, 2006
“Experience is something you don't get until just after you
need it.”
- Olivier
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
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 %
Modulus returns remainder of division between two integers
% cannot be used on float or double
Arithmetic Operators
Division between two integers results in an integer.
The result is truncated, not rounded
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
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;
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