var - if - loops - ......

1. File Structure using C++

2. Simple Example

3. #include<iostream>
 #Include
 means read me before you compile and do what I say essentially.
 means that you're signaling the compiler to include some kind of file
or library that is needed in order for some function to execute in your
source file.
 < and >
 just enclosures for the compiler to read between and import
accordingly.
 *stream
 <iostream> is a library for basic input and out put controls since C++
alone contains no facilities for IO.

4. #include<iostream>
• The #include is a "preprocessor" directive that
tells the compiler to put code from the header
called iostream into our program before
actually creating the executable.
• By including header files, you gain access to
many different functions.
• For example, the cout function requires
iostream

5. using namespace std;
• This line tells the compiler to use a group of
functions that are part of the standard library
(std).
• By including this line at the top of a file, you
allow the program to use functions such as
cout

6. int main()
• This line tells the compiler that there is a
function named main, and that the function
returns an integer, hence int.
• The "curly braces" ({ and }) signal the
beginning and end of functions and other
code blocks.

7. Cout<<“Welcome C++”;
• The cout object is used to display text.
• It uses the << symbols, known as "insertion
operators", to indicate what to output.

8. Declaring Variables in C++

9. Variables in C++
• // operating with variables
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• // declaring variables:
• inta, b;
• Int result;
• // process:
• a = 5;
• b = 2;
• a = a + 1;
• result = a - b;
• // print out the result:
• cout << result;
• // terminate the program:
• return0;
• }

10. Scope of variables

11. Initialization of variables
• inta = 0;
• int a (0);

12. Initialization of variables
• // initialization of variables
• #include <iostream>
• using namespace std;
• intmain ()
• {
• inta=5; // initial value = 5
• Int b(2); // initial value = 2
• Int result; // initial value undetermined
• a = a + 3;
• result = a - b;
• cout << result;
• return0;
• }

13. Introduction to strings
• // my first string
• #include <iostream>
• #include <string>
• using namespace std;
• Int main ()
• {
• string mystring = "This is a string";
• cout << mystring;
• Return 0;
• }

14. Introduction to strings
• string mystring = "This is a string";
• string mystring ("This is a string");

15. Constants (#define)
• // defined constants: calculate circumference
• #include <iostream>
• using namespace std;
• #define PI 3.14159
• #define NEWLINE 'n'
• Int main ()
• {
• Double r=5.0; // radius
• Double circle;
• circle = 2 * PI * r;
• cout << circle;
• cout << NEWLINE;
• Return 0;
• }

16. Declared constants (const)
• const int pathwidth = 100;
• const char tabulator = 't';

17. Operators: Assignment (=)
• // assignment operator
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• inta, b; // a:?, b:?
• a = 10; // a:10, b:?
• b = 4; // a:10, b:4
• a = b; // a:4, b:4
• b = 7; // a:4, b:7
• cout << "a:";
• cout << a;
• cout << " b:";
• cout << b;
• return0;
• }

18. Compound assignment

19. • // compound assignment operators
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• inta, b=3;
• a = b;
• a+=2; // equivalent to a=a+2
• cout << a;
• return0;
• }

20. Increase and decrease (++, --)

21. Conditional operator ( ? )
• // conditional operator
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• inta,b,c;
• a=2;
• b=7;
• c = (a>b) ? a : b;
• cout << c;
• return0;
• }

22. Conditional operator ( ? )
• 7==5 ? 4 : 3 // returns 3, since 7 is not equal
to 5.
• 7==5+2 ? 4 : 3 // returns 4, since 7 is equal to
5+2.
• 5>3 ? a : b // returns the value of a, since 5 is
greater than 3.
• a>b ? a : b // returns whichever is greater, a
or b.

23. Basic Input/Output
• // i/o example
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• inti;
• cout << "Please enter an integer value: ";
• cin >> i;
• cout << "The value you entered is "<< i;
• cout << " and its double is "<< i*2 << ".n";
• return0;
• }

24. cin and strings
• // cin with strings
• #include <iostream>
• #include <string>
• using namespacestd;
• intmain ()
• {
• string mystr;
• cout << "What's your name? ";
• getline (cin, mystr);
• cout << "Hello "<< mystr << ".n";
• cout << "What is your favorite team? ";
• getline (cin, mystr);
• cout << "I like "<< mystr << " too!n";
• return0;
• }

25. Conditional structure: if and else
• if(x > 0)
• cout << "x is positive";
• else if(x < 0)
• cout << "x is negative";
• else
• cout << "x is 0";

26. The while loop
• // custom countdown using while
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• intn;
• cout << "Enter the starting number > ";
• cin >> n;
• while(n>0) {
• cout << n << ", ";
• --n;
• }
• cout << "FIRE!n";
• return0;
• }

27. The do-while loop
• // number echoer
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• unsigned longn;
• do{
• cout << "Enter number (0 to end): ";
• cin >> n;
• cout << "You entered: "<< n << "n";
• } while(n != 0);
• return0;
• }

28. The for loop
• // countdown using a for loop
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• for(intn=10; n>0; n--) {
• cout << n << ", ";
• }
• cout << "FIRE!n";
• return0;
• }

30. Jump statements (break)
• // break loop example
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• intn;
• for(n=10; n>0; n--)
• {
• cout << n << ", ";
• if(n==3)
• {
• cout << "countdown aborted!";
• break;
• }
• }
• return0;
• }

31. continue
• // continue loop example
• #include <iostream>
• using namespacestd;
• intmain ()
• {
• for(intn=10; n>0; n--) {
• if(n==5) continue;
• cout << n << ", ";
• }
• cout << "FIRE!n";
• return0;
• }

32. goto
• // goto loop example
• #include <iostream>
• using namespace std;
• Int main ()
• {
• Int n=10;
• loop:
• cout << n << ", ";
• n--;
• if(n>0) goto loop;
• cout << "FIRE!n";
• return0;
• }