Library Functions

1. Library Functions

2. 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 106

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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 = 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 CSCE 106

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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 106

7. Input/Output Manipulators CSCE 106

8. 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 106

9. 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 106

10. 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 106

11. “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 literals stringinstructor, student = “Omar”; CSCE 106

12. “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 106

13. “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 106

14. “string” Class (cont’d) • Attributes include: • character sequence it stores • length • Accessing String Operations: • Member functionslength() 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 106

15. “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 106

16. “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 106

17. 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 106

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19. 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 106

20. Next lecture will be about Selection/Decision in C++ CSCE 106