1. Correction of the Handout #include //Preprocessor using namespace std; int main (){ ………….. return 0; } A namespace is a named group of definitions. When objects that are defined within a namespace are used outside of that namespace, either their names must be prefixed with the name of the namespace or they must be in a block that is preceded by a using namespace statement. Namespaces make it possible for a program to use different objects with the same name, just as different people can have the same name. The cout object is defined within a namespace named std (for “standard”) in the header file. Throughout the rest of this class, every program is assumed to begin with the two lines #include using namespace std;

2. Week 3 In this class, you will learn about: Program Structure, Actions and Data Types Data Type: Variables Output and Input action: function cout > Assignment Simple calculations Reference: Programming with C++, Theory and Problems of, Second Edition; John R Hubbard (McGraw Hill, 2000, Schaum's Outline Series)

3. Data Type: Variables Variables Name of a variable –A variable has a name, which is given by the programmer by declaration or definition. When the name is given, the memory for it is specified. Rules for creating names of variables –Rule 1: a name starts with a letter. –Rule 2: a name is unique, which should be different from other words in the program. –Rule 3: names are sensitive to letters upper case or lower case. Doug is not equivalent to doug. –Rule 4: names should be meaningful.

4. Data Type: Variables For example, int alice; name of variable: alice type: int(eger) tail: ; Using namespace std

5. Data Types

6. Part of Integral Type

7. Float type example It shows that the 32 bits it uses to store a float are partitioned into 3 parts: 23 bits for the mantissa, 8 bits for the exponent, and 1 bit for the sign. The 23-bit mantissa produces a floating-point value with 6 significant digits, and the 8-bit exponent yields a range in magnitude from about 10–37 to about 3 × 1038. i.e., 0.0000000000000000000000000000000000001 < |x| < 300,000,000,000,000,000,000,000,000,000,000,000,000 for any variable x declared to have type float.

8. A new variable : char (character data) Definition –A char variable is defined to hold a single character that appears on the keyboard. –Difference between a char and a string is that a char is a single character while a string is a collection of serial characters. Declaration –char c; Input a char variable from keyboard A space cannot be input from keyboard

9. A new variable : char (character data)

11. Output action: function cout<< More actions by using a back slash \ The sign \ is not a normal character but a control character to instruct the computer to take an action corresponding to next character. See table below, Escape characterEffect\nNewline\tHorizontal tab\rCarriage return\bBackspace\aBell or beep\\Backslash\”Double quote\’Single quote\?Question mark

12. Input action: input function cin>> Assignment We have seen that one way of assigning a variable with a value is to input a number of digits on keyboard. Another important way is to use an assignment statement. For example (assignment1.cpp),

13. Simple calculations

15. Integer Calculation Example int main() { // tests operators +,-,*,/,and %: int m=54; int n=20; cout << "m = " << m << " and n = " << n << endl; cout << "m+n = " << m+n << endl; // 54+20 = 74 cout << "m-n = " << m-n << endl; // 54-20 = 34 cout << "m*n = " << m*n << endl; // 54*20 = 1080 cout << "m/n = " << m/n << endl; // 54/20 = 2 cout << "m%n = " << m%n << endl; // 54%20 = 14 Return 0; }

16. Prefix and postfix increment Example:k = ++x;//prefix increment is equivalent to: x = x + 1; //increment n first k = x;//assign x’s value to k Example:k = x++;//postfix increment is equivalent to k = x;//assign x’s value to k x = x + 1;//and then increment x

17. Applying the Pre-increment and Post-increment Operators int main() { // shows the difference between m++ and ++m: int m,n; m = 44; n = ++m; // the pre-increment operator is applied to m cout << "m = " << m << ", n = " << n << endl; m = 44; n = m++; // the post-increment operator is applied to m cout << "m = " << m << ", n = " << n << endl; }

18. COMPOSITE ASSIGNMENT OPERATORS The standard assignment operator in C++ is the equals sign =. In addition to this operator, C++ also includes the following composite assignment operators: +=, -=, *=, /=, and %=. When applied to a variable on the left, each applies the indicated arithmetic operation to it using the value of the expression on the right.

19. Applying Composite Arithmetic Assignment Operators int main() { // tests arithmetic assignment operators: int n=22; cout << "n = " << n << endl; n += 9; // adds 9 to n cout << "After n += 9, n = " << n << endl; n -= 5; // subtracts 5 from n cout << "After n -= 5, n = " << n << endl; n *= 2; // multiplies n by 3 cout << "After n *= 2, n = " << n << endl; n / = 3; // divides n by 9 cout << "After n /= 3, n = " << n << endl; n %= 7; // reduces n to the remainder from dividing by 7 cout << "After n %= 7, n = " << n << endl; }