Library Functions

CSCE 1062 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}

CSCE 1063

4 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 = sqrt(x); z = sqrt(x+w);  pow(x,y) x = 2.0; z = 3; y = pow(x,z); function call function name arguments

CSCE 1065

6 “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 ;

CSCE 1067 Input/Output Manipulators

CSCE 1068 Exercise Write 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.

CSCE 1069 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

CSCE 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

CSCE “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  Needed for using string identifiers/objects, but not needed for literals string instructor, student = “Omar”;

CSCE “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

CSCE “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

CSCE “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)

CSCE “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);

CSCE “string” Class (cont’d)  Inserting characters into a string cout << student.insert(0, “Mr. ”) << endl;  Replacing portion of a string cout << student.replace(14, 3, “edy”) << endl;  Deleting portion of a string cout << student.erase(3, 1) << endl;

CSCE 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

CSCE 10618

CSCE 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

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