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1992-2012 by Pearson Education, Inc. & John Wiley & SonsSome portions are adopted from C++ f or Everyone by Horstmann

ENGR 1200U Introduction to Programming

Lecture 6

Simple C++ Programs (Chapter 2) (contd)

Dr. Eyhab Al-Masri

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A symbolic constant is defined in a declaration statementusing the modifier const.

A symbolic constant allocates memory for an object thatcan not be modified during execution of the program. Any attempt to modify a constant will be flagged as a syntax

error by the compiler.

A symbolic constant must be initialized in the declarationstatement.

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1992-2012 by Pearson Education, Inc. & John Wiley & SonsSome portions are adopted from C++ f or Everyone by Horstmann

C++ Operators

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The assignment operator (=) is used in C++ toassign a value to a memory location.

The assignment statement:x1 = 1. 0;

assigns the value 1. 0 to the variable x1.

Thus, the value 1. 0 is stored in the memory location

associated with the identifier x1.(Note: x1 must have been previously declared.)

0 0 0 0 0 1 0 0

8-bit representation

Assignment Operators

integer part fractional part

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Because different types are different representations,frequently we need to convert between types.

Sometimes these conversions may loose information.

Conversion from lower types to higher types results in noloss of information.

Conversion from higher types to lower types may looseinformation.

High:

Low:

long doubledoublefloatlong integerintegershort integer

Assignment Operators contd)

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Assignment operators must not be confused

with equality (==)

stores a new value (in this case the

value of y1) in x1 replacing any

previously stored value

Assignment Operators contd)

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Increment Operator ++ post increment x++; pre increment ++x;

Decrement Operator - - post decrement x- -; pre decrement - -x;

For examples assume k=5 prior to executing thestatement.

m= ++k; // both m and k become 6

n = k- -; // n becomes 5 and k becomes 4

Increment and Decrement Operatorscontd)

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If c = 5, then

cout

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Most programs perform arithmetic calculations

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The five operators (* / % + -) arebinary operators - operators that require twoarguments (i.e. operands).

C++ also include operators that require only asingle argument unary operators. For example, a plus or a minus sign preceding an

expression can be unary operators: (e.g. - x2).

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Division between two integers results in aninteger.

The result is truncated, not rounded

Example:The expression 5/3 evaluates to 1The expression 3/6 evaluates to 0

Integer Division and Remainder

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The % operator computes the remainder of aninteger division.

It is called the modulus oper tor(also modulo and mod)

It has nothing to do with the % key on a calculator

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Hi, Im Penny.

Integer Division and Remainder

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You wanna break

me open for what?

Whats a dollar?

Integer Division and Remainder

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Time to break open the piggy bank.

You want to determine the value in dollars and

cents stored in the piggy bank.

You obtain the dollars through an integer division

by 100.

The integer division discards the remainder.

To obtain the remainder, use the % operator:

int pennies = 1729;

int dollars = pennies / 100; // Sets dollars to 17int cents = pennies % 100; // Sets cents to 29

Integer Division and Remainder

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dollars = / 100;

cents = % 100;

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When a floating-point value is assigned to an integer variable,the fractional part is discarded:

double price = 2.55;

int dollars = price;

// Sets dollars to 2

You probably want to round to the nearest integer.To round a positive floating-point value to the nearest integer,add 0.5 and then convert to an integer:

int dollars = price + 0.5;

// Rounds to the nearest integer

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What about this?

Inside the parentheses is easy:

1 + (r / 100)But that raised to the n?

1001

r n

b

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In C++, there are no symbols for powers and roots.To compute them, you must call functions.

The C++ library defines many mathematical functionssuch as sqrt (square root) andpow (raising to apower).

To use the functions in this library, called the cmathlibrary, you must place the line:

#include at the top of your program file

It is also necessary to includeusing namespace std;at the top of your program file.

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The power function has the base followed by a comma

followed by the power to raise the base to:

pow(base, exponent)

Using thepow function:

b + pow(1 + r / 100, n) 1001

r n

b

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Binary operations on two values of same typeyield a value of that type (e.g. dividing twointegers results in an integer).

Binary operations between values of differenttypes is a mixed operation. Value of the lower type must be converted to the higher

type before performing operation.

Result is of the higher type.

Mixed Operations

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The cast operator The cast operator is a unary operator that requests that thevalue of the operand be cast, or changed, to a new type for

the next computation. The type of the operand is notaffected. Example:

int count(10), sum(55);

double average;

average = (double)sum/count;

Memory snapshot:

int count

int sum

double average

10

55

5.5

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Overflow answer too large to storeExample: using 16 bits for integersr esul t = 32000 + 532;

Exponent overflow answers exponent is too largeExample: using float, with exponent range 38 to 38r esul t = 3. 25e28 * 1. 0e15;

Exponent underflow answers exponent too small

Example: using float, with exponent range 38 to 38r esul t = 3. 25e- 28 * 1. 0e- 15;

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

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

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

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

%= x%=y; x=x%y;

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C++ follows rules of operator precedence, which are generally the sameas those followed in algebra

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