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OperatorsArithmetic OperatorsAssignment OperatorsIncrement/Decrement OperatorsRelational OperatorsLogical Operators

ExpressionStatementsIntroduction to Library Functions

Precedence of OperatorsEvaluation the following Expressions:

a) 4 + 7 * 6 / 3 – 5b) ++ 23 / - 3 + 3 --

Summary of Operators

Defining constants

const Qualifier

#define directive

Automatic Type Conversion and Casts

int count = 100;float avgWeight = 70F;double totalWeight = count * avgWeight;cout<<“The total weight in this room = ”<<totalWeight;

Automatic Type Conversion , Compiler handles the type conversion

Static Castsint result;float a = 4.0;result = a * 3.56;

<<Compiler Signals a WARNING!>>

How do you cast to another type?>>Up-Cast>>Down-Cast

Implicit Type Conversion• When an operator’s operands are of

different data types, C++ will automatically convert them to the same data type.

• When a value is converted to a higher data type, it is said to be prompted.

• To demote a value means to convert it to a lower data type.

Two Rules

Rule 1: When an operator works with two values of different values of different data types, the lower-ranking value is prompted to the type of the higher-ranking value.

Rule 2: When the final value of and expression is assigned to a variable, it will be converted to the data type of that variable.

Explicit Type Conversion

[A type cast expression lets you manually promote or demote a value in the same way that automatic conversion takes place.]

Syntax

static_cast <DataType>(Value)

A variable or Literal value

Data Type you wish to convert it to

int main(){

int books, months;double booksPerMonth;

cout<<“How many books do you plan to read?”cin>>books;

cout<<“How many month will it take you to read them?”cin>>months;

booksPerMonth = books/months;cout<<“That is”<<booksPerMonth<<“books per month.\n”;

system(“pause”);return 0;}

How would you prevent the INTEGER DIVISION?

Quiz _1 : Implement an Pseudocode

Write a program that implements the following algorithm.

Start Read the total hours the employee has worked, TotalHours Read the hourly rate of pay for the employee, HourlyRate GrossSalary = TotalHours * HourlyRate Tax = GrossSalary * 0.1 NetSalary = GrossSalary - Tax

Display NetSalary Stop

Quiz _2:Currency

[Write a program that will convert U.S. dollar amounts to Japanese yen and to euros. The conversion factors to use are 1dollar = 108.5 yen and 1 dollar = 0.8218 euros]

[Solutions to the Quiz Questions]

Library Functions

Yared SemuAddis Ababa Institute of Technology

April 2012

Library Functions

• In C++, we make extensive use of library functions to accomplish tasks.

–Mathematical Functions–IO Manipulators

Mathematical FunctionsThe mathematical functions allow us to do mathematical operations.These operations include:

• raising a number to a certain power,• computing the square root of a number,• computing the cosine of an angle, etc... .

These functions are defined in the header file math.h (or cmath in standard C++).

#include <cmath>

Mathematical Functions …

sqrt is the name of the function that performs the square root operation. This function takes one argument of type double and returns a result of type double.

Multiple Arguments• When a function takes multiple

arguments, they are separated by commas inside the parenthesis.

• This statement computes 3 raised to 4.

Mathematical Functions … The function that computes the power of two numbers is :

More examples of mathematical functions are:

IO Manipulators• IO Manipulators are operators used with the

insertion operator (<<) to modify or manipulate the way data is displayed.

Other IO manipulators, which take arguments, are defined in the iomanip.h (or iomanip in standard C++) header file.

#include <iomanip>

Commonly Used Manipulators

General Output

Manipulator Range Description

endl now Write a newline ('\n') and flush buffer.

setw(n) next •Sets minimum field width on output. (Note: A field is an area on a computer screen, where information such as characters or numbers can be entered and manipulated)•Use left and right to justify the data appropriately in the field. •Output is right justified by default. e.g. cout<<setw(7)<<n<<endl

width(n) next Same as setw(n)

IO ManipulatorsGeneral Output

Manipulator Range Description

left now •Left justifies output in field width.•Only useful after setw(n).

right next •Right justifies output in field width. •Since this is the default, it is only used to override the effects of left. •Only useful after setw(n).

setfill(ch) all •Only useful after setw.• If a value does not entirely fill a field, the character ch will be used to fill in the other characters. •Default value is blank.•E.g. cout << setw(4) << setfill('0') << n << endl;

IO ManipulatorsFloating point output

Manipulator Range Description

setprecision(n) all •Sets the number of digits printed to the right of the decimal point. •This applies to all subsequent floating point numbers written to that output stream. •However, this won't make floating-point "integers" print with a decimal point. •It's necessary to use fixed for that effect

fixed all •Used fixed point notation for floating-point numbers.• Opposite of scientific. •If no precision has already been specified, it will set the precision to 6

scientific all •Formats floating-point numbers in scientific notation.• Opposite of fixed.

IO Manipulators(Example)What is the output of this program?

Example- IO Manipulators• Write a program that displays the

output show below.

Exercises