1. C++ Basics Prof. Shermane Austin

2. Learning Programming Language Basics Data Types – simple Expressions Relational and Logical Operators Conditional Statements Arrays Iteration Memory Allocation I/O Functions

3. Hello World //Simple C++ program #include //input and output library #include //string library using namespace std; // predefined objects int main() //first function, { //function delimiter cout << “Hello world!” << endl; //output stream return 0; //ends execution and returns ]

4. Simple Data Types Int – 32 bit, optional qualifiers: long, short Float – 32 bit, IEEE floating point Double – 64 bit, optional qualifer: long Char – 8 bit Byte – 8 bit

5. Operators Arithmetic – +, -, /, * –% - modulus or remainder, integer only, e.g. 23%4 Relational –, =, !=, == –(c == a) \\ common error is omitting one of the = –Be careful using != or == with floating point values, rounding occurs at the machine level Logical –And &&, e.g. (c = b) –Or ||, e.g. (c = b)

6. Operator shortcuts – Compound Assignment Increment, Decrement ++, -- a = a + 1; \\can be written as a++; a++, ++a, a--, --a Position of operator is important, e.g. b = f(a++); \\a is incremented after f(a) call\\a c = f(++a); \\a is incremented before f(a) call\\a Compound Assignment Operators int a; … a = a + 5; a += 5; Can be used with all arithmetic operators

7. Exercise - 1 Compute volume of an object Read in: –Object mass (grams) –Object density (grams per cubic centimeter) Output: Volume (cubic centimeters) Relationship: Density = Mass/Volume

8. Code Needs Determine variables (with types needed) Issue prompts – use cout, e.g. Cout << “Object Mass?” << endl; Read in values – use cin, e.g. Cin >> mass; Compute Distance and Velocity

9. Conditional Expressions Any combination of logical and relational operators Use () as needed Examples: Simple if statement if( a < b) s1 else s2

10. If/else statement General format – single statement execution on true condition Long format – multiple statement execution on true condition General rule: more than one statement under if and/or else condition requires {} Short-hand format – single statement Nested if statements

11. If – single statement Format: if(expression) s1; else s2;

12. If – multiple statements Format: if(expression) { s1; s2; … } else { s1; s2; … }

13. If shorthand Used only with single statements Format: Expression ? S1 : s2; Example: c != b ? c++ : b++; Example: int a,b; … int min = a <= b ? a : b ;

14. Short-circuit evaluation && - evaluation terminates with first false condition || - evaluation terminates with first true condition Done to insure objects can be properly manipulated, e.g. –(i != 0) && ((j/i) > 5)

15. Arrays Included in C++ for backward compatibility with C Arrays less popular and class representation of lists, especially the vector class more frequently used Vector class is an example of container classes is defined in the Standard Template Library (STL)

16. Simple arrays - Declaration const int N = 20; const int M = 40; const int MaxListSize = 1000; // Note: const qualifier used to denote constant values //Declaration examples: int a[10]; float c[M*N]; int Values[MaxListSize];

17. Simple Arrays - Referencing Array elements are referenced using subscripts or indices First index in C++ is 0 Examples: a[0] = b; a[i++] = a[j] + 3; a[a[k]] = 12; Warning: No automatic checking for array boundaries. Illegal subscripts will result in inaccurate memory references or storage

18. Simple Array - Initialization Int frequency[5] = {0,0,0,0,0}; Int total[5] = {0}; // first element set to 0, remainder are uninitialized and default at 0 Int digits[] = {0,1,2,3,4,5,6,7,8,9}; Int zero[] = {0}; //one-element array

19. Iteration For-loops While-loops

20. Iteration using while Format: while (conditional expression) { s1; … } Statement in the block are executed as long as condition is true If condition is evaluated to false, statements are never executed

21. Interation using for Format: for (ForInit ; ForExpression; PostExpression) { } ForInit – initialization step to start loop ForExpression – logical expression PostExpression – next iteration of loop

22. For examples for( i = 0; i<= maxsize; i++) { } for(j=minsize; j < maxsize; j+=2) { } for(k = maxsize; k > minsize; k--) { }

23. Exercises Compute n! using a for loop Compute the nth Fibonacci term using a while loop

24. Example, compute roots of a quadratic equation: //Quadratic roots #include Using namespace std; int main() { double a, b, c; cout << “Coefficients for quadratic equation: “; cin >> a >> b >> c; if ((a != 0) && ((b*b – 4*a*c) > 0)) { double radical = sqrt(b*b – 4 * a * c); double root1 = (-b + radical) / (2 * a); double root2 = (-b – radical) / (2 * a); cout << “ roots are “ << root1 << “ and “ << root2 << endl; } else { cout << “ No real roots “ << endl; } return 0; }

25. Compute area of a circle #include Using namespace std; const float Pi = 3.1415 int main() { float radius; cout << “Enter radius: ”; cin >> radius; //compute area float area = Pi * radius * radius; //output cout << “Area = “ << area; }

26. More general using functions #include Using namespace std; float CircleArea(float r) { const float Pi = 3.1415; return Pi * r * r; } int main() { float radius; cout << “Enter radius: ”; cin >> radius; //compute area float area = CircleArea(radius); //output cout << “Area = “ << area; }

27. Function prototyping Functions cannot be used until they are defined Can create problems with functions calling other functions Use prototype conventions Define function prototype before main Implement function after main

28. Prototype Example #include Using namespace std; float CircleArea(float r); int main() { float radius; cout << “Enter radius: ”; cin >> radius; //compute area float area = CircleArea(radius); //output cout << “Area = “ << area; } float CircleArea(float r) { const float Pi = 3.1415; return Pi * r * r; }

29. Homework Write a program for integrating a quadratic polynomial User input will be –Quadratic coefficients: a1, a2, a3 –Interval of interest : n1, n2 Output will be the area