Week 1-2 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)

Program Structure, Actions and Data Types C++ Program Structure #include main() { cout<<"HEY, you, I'm alive!"; // output a string. } –The program is saved as a file that should be named. In this example, the name of the file is cout1a.cpp..cpp –The #include is called a preprocessor directive which tells the computer compiler to include the header file iostream.h in our program cout1a.cpp. –The next part is main(). –The body of the –The lines for the body of a program is called statements, for example, cout –Comment lines

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.

Data Type: Variables For example, int alice; name of variable: alice type: int(eger) tail: ;

Data Types

Part of Integral Type

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 × i.e., < |x| < 300,000,000,000,000,000,000,000,000,000,000,000,000 for any variable x declared to have type float.

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

A new variable : char (character data)

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

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),

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

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; }

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.

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 4 cout << "After n %= 7, n = " << n << endl; }

Simple calculations

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; // = 74 cout << "m-n = " << m-n << endl; // = 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; }