Library Functions

Library Functions

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Outline cmath class library functions {section

3.2} iomanip class library functions {section

8.5} string class library functions {sections

2.3 & 3.7} Object Orientation (OO) {section 1.3}

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Math Functions Math functions are contained in the header file/class

cmath Examples of some predefined math functions are:

sqrt(x) x = 16.0;y = sqrt(x);z = 5.7 + sqrt(x);z = sqrt(x+w);

pow(x,y) x = 2.0;z = 3;y = pow(x,z);

function call

function name

arguments

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“iomanip” Class A C++ library containing manipulators to control

format of output. setw(n)

n is int. controls the width of the following output field only. the default width is 0. cout << setw(4) << x ;

setprecision(n) n is int. sets the precision to n decimal places. it remains in effect for future output (until changed) the default is 6 decimal places. cout << setprecision(4) << x ;

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Input/Output Manipulators

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ExerciseWrite a complete C++ program to calculate, and output the future value (F), rounded to the nearest piaster, of a single cash flow (C) invested in a bank for (n) years at a nominal interest rate (r). F is calculated from the following formula:

where C, r, and n are input by the user. nrCF 1

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Solution Steps Problem statement/Requirements

phase. Already done, as problem is simple

Analysis phase. Problem input

• float C, r, n Problem output

• float F (rounded to 2 decimal places) Additional program variables

• NA

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Solution Steps (cont’d) Processing formulas

• F = C * pow(1+r, n)

Design phase. Draw the flow chart. Implementation phase. Transform your

flow chart to a C++ program. Testing phase.

Test results using various input combinations

Verify results by hand or with calculator

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“string” Class string literals are enclosed in double

quotes, e.g.: “Enter miles: “ “ABC” “B” “true” “1234”

string as a data type is not built-in in C++, it comes from a predefined library

#include <string> Needed for using string identifiers/objects,

but not needed for literalsstring instructor, student = “Omar”;

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“string” Class (cont’d) Common operations on string objects:

<< >> = +cin >> instructor; // reads up to blank or return

cout << student << endl; (New lines: endl; or ‘\n’;) + puts strings together (concatenation)

student = student + “ “ + “Mohammad”; Note that we need a space between names

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“string” Class (cont’d) Can read string with blanks

getline(cin, lastName, ‘\n’); // reads an entire line

Special/control characters’\n’ newline’\b’ backspace’\t’ tab‘\’’ single quote‘\”’ double quote‘\\’ backslash

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“string” Class (cont’d) Attributes include:

character sequence it stores length

Accessing String Operations: Member functions length() and at() These functions can be called using dot

notation (syntax: object. function-call) Applies the identified operation to the named

object, e.g.: student. length( ), student. at(0)

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“string” Class (cont’d)cout << student.length() << endl;cout << student.at(0) << student.at(5) << endl;cout << student.at(student.length() – 1) << endl;

Additional Member Functions: Searching for a string

cout << student.find(“am”) << endl; Assign a substring to a string object

instructor.assign(instructor,0,3);

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“string” Class (cont’d) Inserting characters into a string

cout << student.insert(0, “Mr. ”) << endl;

Replacing portion of a stringcout << student.replace(14, 3, “edy”) << endl;

Deleting portion of a string cout << student.erase(3, 1) << endl;

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Object Orientation C++ is an object oriented language C++ promotes code reuse with predefined

classes, that has functions, defined in the standard library

Classes extend C++ A class has data/attributes and

functions/methods An instance of a class is an object. Classes are organized in a hierarchy

Super classes Sub classes

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Object Orientation (cont’d) Important properties of OO:

Abstraction• Extract the relevant properties of an object

while ignoring inessential details Encapsulation

• Breaking down an object into parts, hiding and protecting its essential information, and supplying an interface to modify the information in a controlled and useful manner

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Next lecture will be about Selection/Decision in C++