Final project powerpoint template (fndprg) (1)


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Final project powerpoint template (fndprg) (1)

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  4. 4. In programming, a switch, case, select or inspect statement is a type of selection control mechanism thatexists in most imperative programming languages suchas Pascal programming language, Ada programminglanguage, C/C++ programming language, C#programming language, Java programminglanguage, and so on. It is also included in several othertypes of programming languages. Its purpose is toallow the value of a variable or expression to controlthe flow of program execution via a multiwaybranch (or "goto", one of several labels). The mainreasons for using a switch include improving clarity, byreducing otherwise repetitive coding, and (ifthe heuristics permit) also offering the potential forfaster execution through easier compiler optimization inmany cases.
  5. 5. Like if statements, controls the flow ofprograms by allowing programmers to specify differentcode that should be executed in various conditions. Inparticular, a switch statement compares the value of avariable to the values specified in case statements. Whena case statement is found whose value matches that ofthe variable, the code in that case statement is run.The break keyword exits the switch statement, and istypically used at the end of each case. Without a breakstatement, the switch statement will continue executingthe following expressions ("falling-through") until a break, orthe end of the switch statement is reached.
  6. 6. switch (expression){case constant1: codes to be executed if expression equals to constant1; break;case constant2: codes to be executed if expression equals to constant3; break; . . .default: codes to be executed if expression doesnt match to any cases;}
  7. 7. #include <iostream>using namespace std;void playgame(){ cout << "Play game called";}void loadgame(){ cout << "Load game called";}void playmultiplayer(){ cout << "Play multiplayer game called";}int main(){ int input; cout<<"1. Play gamen"; cout<<"2. Load gamen"; cout<<"3. Play multiplayern"; cout<<"4. Exitn"; cout<<"Selection: "; cin>> input; switch ( input ) { case 1: playgame(); break; case 2: loadgame(); break; case 3: playmultiplayer(); break; case 4: cout<<"Thank you for playing!n"; break; default: cout<<"Error, bad input, quittingn"; break; } cin.get();}
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  9. 9. This is a sample programming, in which not all of the proper functionsare actually declared, but which shows how one would use switch in a program. This program will compile, but cannot be run until the undefined functions are given bodies, but it serves as a model (albeit simple) for processing input. If you do not understand this then trymentally putting in if statements for the case programming statements. Default simply skips out of the switch case programming construction and allows the program to terminate naturally. If you do not likethat, then you can make a loop around the whole thing to have it wait for valid input. You could easily make a few small functions if you wish to test the code.
  10. 10. #include <iostream>using namespace std;int main(){cout << "Enter a number between 1 and 5!" << endl;int number;cin >> number;switch(number){case 1: //if (number == 1)cout << "one";break;case 2: //else if(number == 2) and so on...cout << "two";break;case 3:cout << "three";break;case 4:cout << "four";break;case 5:cout << "five";break;default: //if number is NOT 1,2,3,4 or 5cout << number << " is not between 1 and 5!";}cout << endl;system("pause");}
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  12. 12. break; The same result for multiple valuesThe break is used to break out from the switch/case programming If you want to execute the same code in morestatement. Without break the program will execute all the code cases, you don`t have to write that codeafter the selected one. For example, if we don`t use breaks in the multiple times, just write it like in the bellowthis code, and the user inputs 3, the program will show: example:threefourfive3 is not between 1 and 5! switch (myvariable){instead of case 1:three case 2:Write the above code in your compiler and try it out to see it with case 3:your own eyes. cout << "myvariable is 1,2 or 3"; }default:The default case is optional, this is executed when none of theprevious cases are executed or when you forget the break;.Note: The cases (including the default case) are followed by acolon, not semicolon!Note: This is very important! A variable can`t be used as possiblevalue of a case statement! Example of how NOT to do:int myvariable = 1;switch (x){case myvariable: //this is NOT valid//code to execute}
  13. 13. #include <iostream.h>using namespace std;int main(void) { int day; cout << "Enter the day of the week between 1-7::"; cin >> day; switch(day) { case 1: cout << "Monday"; break; case 2: cout << "Tuesday"; break; case 3: cout << "Wednesday"; break; case 4: cout << "Thursday"; break; case 5: cout << "Friday"; break; case 6: cout << "Saturday"; break; default: cout << "Sunday"; break; } }
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  15. 15. Syntax: Switch statement programming switch(expression) compares the value of an expression { against a list of integers or character case constant1:constants. The list of constants are listed Statements using the "case“ programming break statement along with a "break“ case constant2: programming statement to end the Statementsexecution. If no conditions match then break the code under the default statement . is executed. . default Statements }
  16. 16. #include <stdlib.h>#include <stdio.h>int main(void) { int n; printf("Please enter a number: "); scam("%d", &n); switch (n) { case 1: { printf("n is equal to 1!n"); break; } case 2: { printf("n is equal to 2!n"); break; } case 3: { printf("n is equal to 3!n"); break; } default: { printf("n isnt equal to 1, 2, or 3.n"); break; } } system("PAUSE"); return 0;}
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  18. 18. The switch programming statement is used in C++ for testing if a variable is equal to one of a set of values. The variable must be an integer, i.e. integral or non-fractional. The programmer can specify the actions taken for each case of the possible values the variable can have. Thesame operation can be performed by using a series of if, else if, and else statements.
  19. 19. This is the switch programming statement. It indicates that a series of cases will follow in which we will test for equality with variable "n". If n isswitch (n) { equal to any of the values in the following cases, then the first match found will run its encapsulated code. The curly brace, {, encapsulates the case statements. An end curly brace, }, will follow 1: { This is the first case programming statement. It has a set of code printf("n is equal to 1!n"); encapsulated by curly braces, { and }, which are not manditory, but break; serve to make the source code easier to follow. If n is equal to 1, then} the printf() function here will display "n is equal to 1!" on the screen. A break programming statement follows the printf() function. This is required after each case to tell the program to exit out of the switch programming statement. Otherwise, the rest of the code in each of the cases would be run if the break programming statement were not 2: { This is the second case programming statement. If n is equal to 2, then printf("n is equal to 2!n"); the printf() function will be run to display "n is equal to 2!" on the screen. break; The break statement will cause the program to exit out of the switch} statement as desired since we have already found a match for 3: { This is the last case statement. If n is equal to 3, then the printf() function printf("n is equal to 3!n"); will be run to display "n is equal to 3!" on the screen. The break break; statement will cause the program to exit out of the switch statement as} desired since we have already found a match for n. This is the default statement. If a match for n has not been found, thendefault: { the code after the default statement will be run, and the printf() printf("n isnt equal to 1, 2, or 3.n"); function will display "n isnt equal to 1, 2, or 3." on the screen. The break break; statement will cause the program to exit out of the switch statement;} although, since the default statement here comes after the case statements, this break statement inside of the default statement is technically not required. This is the end curly brace that encapsulates the case statements and} the default statement within the switch statement.
  20. 20. #include <iostream.h>int main(){ unsigned short int number; cout << "Enter a number between 1 and 5: "; cin >> number; switch (number) { case 0: cout << "Too small, sorry!"; break; case 5: cout << "Good job!n"; // fall through case 4: cout << "Nice Pick!n"; // fall through case 3: cout << "Excellent!n"; // fall through case 2: cout << "Masterful!n"; // fall through case 1: cout << "Incredible!n"; break; default: cout << "Too large!n"; break; } cout << "nn"; return 0;}
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  22. 22. It is important to note that if there is no break programming statement at the end of a case programming statement, execution will fall through to the next case statement. This is sometimes necessary, but usually is an error. If you decide to let execution fall through, be sure to put a comment, indicating that you didnt just forget the break. The user is prompted for a number. That number is given to the switch programming statement. If the number is 0, the case statement on line 13 matches, the message Too small, sorry! is printed, and the break statement ends the switch. If the value is 5, executionswitches to line 15 where a message is printed, and then falls through to line 16, another message is printed, and so forth until hitting the break on line 20. The net effect of these statements is that for a number between 1and 5, that many messages are printed. If the value of number is not 0-5, it is assumed to be too large, and the default statement is invoked on line 21.
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  24. 24. Looping programming statement are used to repeat a blockof code. Being able to have your program repeatedlyexecute a block of code is one of the most basic but usefultasks in programming -- many programs or websites thatproduce extremely complex output (such as a messageboard) are really only executing a single task many times.(They may be executing a small number of tasks, but inprinciple, to produce a list of messages only requiresrepeating the operation of reading in some data anddisplaying it.) Now, think about what this means: a loop letsyou write a very simple programming statement to produce asignificantly greater result simply by repetition.
  25. 25. The following commands used inC++ for achieving looping: •for loop •while loop •do-while loop
  26. 26. The variable initialization allows you to either declare a variable and give it a value or give a value to an already existing variable. Second, the condition tells the program that while the conditional expression is true the loop should continue to repeat itself. The variable update section is the easiest way for a for loop to handle changing of the variable. It is#include <iostream> possible to do things like x++, x = x + 10, orusing namespace std; // So the program can see cout and endl even x = random ( 5 ), and if you reallyint main(){ wanted to, you could call other functions for ( int x = 0; x < 10; x++ ) { that do nothing to the variable but still cout<< x <<endl; have a useful effect on the code. Notice } cin.get(); that a semicolon separates each of these} sections, that is important. Also note that every single one of the sections may be empty, though the semicolons still have to be there. If the condition is empty, it is evaluated as true and the loop will repeat until something else stops it.
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  28. 28. The basic structure is while ( condition ) { Code to execute while the condition is true } The true represents a boolean expression which could be x == 1 or while ( x != 7 ) (x does not equal 7). It can be any combination of boolean programming statements#include <iostream> that are legal. Even, (while x ==5 || vusing namespace std; // So we can see cout and endl == 7) which says execute the codeint main(){ while x equals five or while v equals 7. int x = 0; // Dont forget to declare variables Notice that a while loop is the same while ( x < 10 ) { // While x is less than 10 cout<< x <<endl; as a for loop without the initialization x++; // Update x so the condition can be met eventually } and update sections. However, an cin.get();} empty condition is not legal for a while loop as it is with a for loop.
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  30. 30. Notice that the condition is tested at the end of the block instead of the beginning, so the block will be executed at least once. If the condition is true, we jump back to the beginning of the block and execute it again. A do..while loop is basically a reversed while loop. A while loop says "Loop while the condition is true, and execute this block of code", a do..while loop says "Execute this block of code, and loop while the condition is true". Keep in#include <iostream> mind that you must include a trailing semi-using namespace std; colon after the while in the above main(){ A common error is to forget that a do..while int x; loop must be terminated with a semicolon x = 0; do { (the other loops should not be terminated // "Hello, world!" is printed at least one time // even though the condition is false with a semicolon, adding to the confusion). cout<<"Hello, world!n"; } while ( x != 0 ); Notice that this loop will execute cin.get();} once, because it automatically executes before checking the condition.
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  32. 32. The while loop executes a block of programming statements whilea condition is true. The basic syntax of a while loop is:while( condition ){//code to execute while condition is true}Here is an example about how to use it. The following program willwrite out the numbers from 1 to 100: #include <iostream> using namespace std; int main(){ int i = 0; while(i < 100){ cout << ++i << endl; } system("pause"); }Before the while loop starts i is declared with the value 0, but thefirst number will be 1, because the ++ is in front of i.
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  34. 34. The for loop is useful when you know how many times you need to repeat a block of code, because the for loop repeats the#include <iostream> code for a specific number of times.using namespace std;int main(){for(int i=1;i<=100;i++){cout << i << endl;}system("pause");}
  35. 35. The basic syntax is:for(integer = starting value; integer <= ending value; integer++){//code to execute}We can use any variable name for the integer, but the default is i or y.Here is an example of using the for loop:Write out the numbers from 1 to 100:#include <iostream>using namespace std;int main(){for(int i=1;i<=100;i++){cout << i << endl;}system("pause");}For the starting and ending value we can use variables, too. For example look at the bellow program which shows all the numbersbetween two numbers:#include <iostream>using namespace std;int main(){cout << "Enter the starting number: ";int startingnum;cin >> startingnum;cout << "Enter the ending number: ";int endingnum;cin >> endingnum;for(startingnum;startingnum <= endingnum;startingnum++){cout << startingnum << endl;}system("pause");}The counting expression can be anything, it can increment or decrement, or any mathematical expression, here are someexamples:for(int i=10;i>0;i--)orfor(int i=1;i<=101;i+=10)orfor(int i=1;i<=101;i*=2)and so on....
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  37. 37. This Presentation is submitted to:Prof. Erwin Globio