Switch case and looping

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Switch case and looping

  1. 1. Switch Case and LoopingA final requirement for programming http://eglobiotraining.com
  2. 2. Programming We first define the word “programming”, it is acomputer language programmers use to developapplications, scripts, or other set of instructions for acomputer to execute. http://eglobiotraining.com
  3. 3. As an individual, I have learned thatprogramming is a very broad because itcomposes many scripts, applications and can beused to run a program that has been part of theprogramming language. http://eglobiotraining.com
  4. 4. At first, programming is confusing becauseyou have so much to understand about codesthat will enable to run a program. Programminghas applications and program development, thebest example for this is the Internet bowser… http://eglobiotraining.com
  5. 5. You have to consider languages to run orwrite your own program, most demandedlanguage in programming is the DEV C++ (a full-featured Integrated Development Environment(IDE)). http://eglobiotraining.com
  6. 6. Switch Case Switch case statements are a substitutefor long if statements that compare a variableto several "integral" values ("integral" valuesare simply values that can be expressed as aninteger, such as the value of a char). http://eglobiotraining.com
  7. 7. basic format for using switch case: switch ( <variable> ) { case this-value: Code to execute if <variable> == this-value break; case that-value: Code to execute if <variable> == that-value break; ... default: Code to execute if <variable> does not equal the value following any of the cases break; } The value of the variable given into switch is compared to the value following each of the cases, and when one value matches the value of the variable, the computer continues executing the program from that point. http://eglobiotraining.com
  8. 8. The condition of a switch statement is a value.The case says that if it has the value of whatever isafter that case then do whatever follows the colon.The break is used to break out of the casestatements. An important thing to note about theswitch statement is that the case values may only beconstant integral expressions. http://eglobiotraining.com
  9. 9. “Break” is a keyword that breaks out of the codeblock, usually surrounded by braces, which it is in. Inthis case, break prevents the program from fallingthrough and executing the code in all the other casestatements. http://eglobiotraining.com
  10. 10. The default case is optional, but it is wise toinclude it as it handles any unexpected cases. Switchstatements serves as a simple way to write long ifstatements when the requirements are met. Often itcan be used to process input from a user. http://eglobiotraining.com
  11. 11. This shows how would you use a Switch in a Program #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: // Note the colon, not a semicolon playgame(); break; case 2: // Note the colon, not a semicolon loadgame(); break; case 3: // Note the colon, not a semicolon playmultiplayer(); break; case 4: // Note the colon, not a semicolon cout<<"Thank you for playing!n"; break; default: // Note the colon, not a semicolon cout<<"Error, bad input, quittingn"; break; } cin.get(); } http://eglobiotraining.com
  12. 12. That program will compile, but cannot be run until theundefined functions are given bodies, but it serves as amodel (albeit simple) for processing input. If you do notunderstand this then try mentally putting in if statements forthe case statements. Default simply skips out of the switchcase construction and allows the program to terminatenaturally. If you do not like that, then you can make a looparound the whole thing to have it wait for valid input. Youcould easily make a few small functions if you wish to test thecode. http://eglobiotraining.com
  13. 13. Looping Loops are used to repeat a block of code.Being able to have your program repeatedlyexecute a block of code is one of the most basicbut useful tasks in programming -- manyprograms or websites that produce extremelycomplex output (such as a message board) arereally only executing a single task many times. http://eglobiotraining.com
  14. 14. (They may be executing a small number oftasks, but in principle, to produce a list ofmessages only requires repeating the operationof reading in some data and displaying it.) Now,think about what this means: a loop lets youwrite a very simple statement to produce asignificantly greater result simply by repetition. http://eglobiotraining.com
  15. 15. One Caveat: before going further, you should understandthe concept of C++s true and false, because it will benecessary when working with loops (the conditions are thesame as with if statements). Three types of Loops: for, while, and do.. http://eglobiotraining.com
  16. 16. FORFor ( variable initialization; condition; variable update ) { Code to execute while the condition is true} http://eglobiotraining.com
  17. 17. The variable initialization allows you to either declare a variable andgive it a value or give a value to an already existing variable. Second, thecondition tells the program that while the conditional expression is truethe loop should continue to repeat itself. The variable update section isthe easiest way for a for loop to handle changing of the variable. It ispossible to do things like x++, x = x + 10, or even x = random ( 5 ), and ifyou really wanted to, you could call other functions that do nothing to thevariable but still have a useful effect on the code. Notice that a semicolon separates each of these sections, that isimportant. 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 isevaluated as true and the loop will repeat until something else stops it. http://eglobiotraining.com
  18. 18. Example: #include <iostream> using namespace std; // So the program can see cout and endl int main() { // The loop goes while x < 10, and x increases by one every loop for ( int x = 0; x < 10; x++ ) { // Keep in mind that the loop condition checks // the conditional statement before it loops again. // consequently, when x equals 10 the loop breaks. // x is updated before the condition is checked. cout<< x <<endl; } cin.get(); } This program is a very simple example of a for loop. x is set to zero, while x is less than 10 it calls cout<< x <<endl; and it adds 1 to x until the condition is met. Keep in mind also that the variable is incremented after the code in the loop is run for the first time. http://eglobiotraining.com
  19. 19. WHILE The basic structure: 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 statements that are legal. Even, (while x ==5 || v == 7) which says execute the code while x equals five or while v equals 7. Notice that a while loop is the same as a for loop without the initialization and update sections. However, an empty condition is not legal for a while loop as it is with a for loop. http://eglobiotraining.com
  20. 20. Example: #include <iostream> using namespace std; // So we can see cout and endl int main() { int x = 0; // Dont forget to declare variables while ( x < 10 ) { // While x is less than 10 cout<< x <<endl; x++; // Update x so the condition can be met eventually } cin.get(); } The easiest way to think of the loop is that when it reaches the brace at the end it jumps back up to the beginning of the loop, which checks the condition again and decides whether to repeat the block another time, or stop and move to the next statement after the block. http://eglobiotraining.com
  21. 21. DO..WHILE are useful for things that want to loop at least once.The Structure: do { } while ( condition ) ; http://eglobiotraining.com
  22. 22. Notice that the condition is tested at the end of the blockinstead of the beginning, so the block will be executed at leastonce. If the condition is true, we jump back to the beginningof the block and execute it again. A do..while loop is basicallya reversed while loop. A while loop says "Loop while thecondition is true, and execute this block of code", a do..whileloop says "Execute this block of code, and loop while thecondition is true". http://eglobiotraining.com
  23. 23. Example: #include <iostream> using namespace std; int main() { int x; x = 0; do { // "Hello, world!" is printed at least one time // even though the condition is false cout<<"Hello, world!n"; } while ( x != 0 ); cin.get(); } Keep in mind that you must include a trailing semi-colon after the while in the above example. A common error is to forget that a do..while loop must be terminated with a semicolon (the other loops should not be terminated with a semicolon, adding to the confusion). Notice that this loop will execute once, because it automatically executes before checking the condition. http://eglobiotraining.com
  24. 24. CODES AND EXPLANATIONS OF THEPROGRAMS HAVE BEEN TESTED http://eglobiotraining.com
  25. 25. LOOPING STATEMENT 1#include <iostream>int main(){ using namespace std; // nSelection must be declared outside do/while loop int nSelection; do { cout << "Please make a selection: " << endl; cout << "1) Addition" << endl; cout << "2) Subtraction" << endl; cout << "3) Multiplication" << endl; cout << "4) Division" << endl; cin >> nSelection; } while (nSelection != 1 && nSelection != 2 && nSelection != 3 && nSelection != 4); // do something with nSelection here // such as a switch statement return 0;} http://eglobiotraining.com
  26. 26. LOOPING STAEMENT 2 #include <iostream> using namespace std; int main() { int nSelection; double var1, var2; do { cout << "Please make a selection: " << endl; cout << "1) Addition" << endl; cout << "2) Subtraction" << endl; cout << "3) Multiplication" << endl; cout << "4) Division" << endl; cin >> nSelection; } while (nSelection != 1 && nSelection != 2 && nSelection != 3 && nSelection != 4); if (nSelection == 1) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1+var2) << endl; } http://eglobiotraining.com
  27. 27. LOOPING STATEMENT 3 if (nSelection == 2) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1-var2) << endl; } if (nSelection == 3) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1*var2) << endl; } if (nSelection == 4) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1/var2) << endl; } return 0; } http://eglobiotraining.com
  28. 28. LOOPING STATEMENT 3 #include <iostream> using namespace std; int main() { int nSelection; double var1, var2; while (1) { do { cout << "Please make a selection: " << endl; cout << "1) Addition" << endl; cout << "2) Subtraction" << endl; cout << "3) Multiplication" << endl; cout << "4) Division" << endl; cout << "5) Exit" << endl; cin >> nSelection; } while (nSelection != 1 && nSelection != 2 && nSelection != 3 && nSelection != 4 && nSelection != 5); if (nSelection == 1) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1+var2) << endl; } http://eglobiotraining.com
  29. 29. LOOPING STATEMENT 4 else if (nSelection == 2) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1-var2) << endl; } else if (nSelection == 3) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1*var2) << endl; } else if (nSelection == 4) { cout << "Please enter the first whole number "; cin >> var1; cout << "Please enter the second whole number "; cin >> var2; cout << "The result is " << (var1/var2) << endl; }else { return 0; } }} http://eglobiotraining.com
  30. 30. LOOPING STATEMENT 5 #include <iostream> using namespace std; // So the program can see cout and endl int main() { // The loop goes while x < 10, and x increases by one every loop for ( int x = 0; x < 10; x++ ) { // Keep in mind that the loop condition checks // the conditional statement before it loops again. // consequently, when x equals 10 the loop breaks. // x is updated before the condition is checked. cout<< x <<endl; } cin.get(); } http://eglobiotraining.com
  31. 31. LOOPING STATEMENT 6#include <iostream>using namespace std;int main(){ int x; x = 0; do { // "Hello, world!" is printed at least one time // even though the condition is false cout<<"Hello, world!n"; } while ( x != 0 ); cin.get();} http://eglobiotraining.com
  32. 32. LOOPING STATEMENT 7#include <iostream>using namespace std;int main (){int n;cout << "Enter the starting number > ";cin >> n;while (n>0) {cout << n << ", ";--n;}cout << "FIRE!n";return 0;} http://eglobiotraining.com
  33. 33. SWITCH CASE 1 SWITCH CASE #include <iostream> using namespace std; int main () { int score; cout << "What was your score?"; cin >> score; if (score <= 25) { cout << "nOuch, less than 25...!"; } http://eglobiotraining.com
  34. 34. SWITCH CASE 2else if (score <= 50) { cout << "nYou score aint great mate.."; } else if (score <= 75) { cout << "nYour pretty good, wel done man!"; } else if (score <= 100) { cout << "nYou got to the top!!!"; } http://eglobiotraining.com
  35. 35. SWITCH CASE 3 else { cout << "nYou cant score higher than 100!!! Cheater!!!!"; } cin.ignore(); cin.get(); return 0;} http://eglobiotraining.com
  36. 36. SWITCH CASE 4#include <iostream>using namespace std;int main(){cout << "Enter a number between 1 and 5!" << endl;int number;cin >> number;if(number == 1){cout << "one";}else if(number == 2){cout << "two";}else if(number == 3){cout << "three";}else if(number == 4){cout << "four";}else if(number == 5){cout << "five";}else{cout << number << " is not between 1 and 5!";}cout << endl;system("pause");} http://eglobiotraining.com
  37. 37. SWITCH CASE 5#include <iostream>using namespace std;int main(){int price_before_discount, RM, dozen, total_price;cout<< "How much is the price before discount for 1 dozen boxes of tissue?n";cout<<"RM ";cin>>price_before_discount;cout<<"nn";cout<< "How many dozen boxes of tissue you buy?n";cin>>dozen;cout<<"nn";switch (dozen){total_price = ((price_before_discount*dozen) * (95/100));case 1: cout<< "Total price is RM ";cout<<RM;cout<<"nn";break;total_price = ((price_before_discount*dozen) * (88/100));case 2: cout<< "Total price is RM ";cout<<RM;cout<<"nn";break;total_price = ((price_before_discount*dozen) * (75/100));case 3: cout<< "Total price is RM ";cout<<RM;cout<<"nn";break;total_price = ((price_before_discount*dozen) * (60/100));case 4 : cout<< "Total price is RM ";cout<<RM;cout<<"nn";break;total_price = ((price_before_discount*dozen) * (40/100));default : cout<< "Total price is RM ";cout<<RM;cout<<"nn";}return 0;} http://eglobiotraining.com
  38. 38. SWITCH CASE 6#include <stdlib.h>#include <stdio.h>int main(void) { int n; printf("Please enter a number: "); scanf("%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;} http://eglobiotraining.com
  39. 39. SWITCH CASE 7#include <iostream>using namespace std;int main(void){ char grade; cout << "Enter your grade: "; cin >> grade; switch (grade) { case A: cout << "Your average must be between 90 - 100" << endl; break; case B: cout << "Your average must be between 80 - 89" << endl; break; case C: cout << "Your average must be between 70 - 79" << endl; break; case D: cout << "Your average must be between 60 - 69" << endl; break; default: cout << "Your average must be below 60" << endl; } return 0;} http://eglobiotraining.com
  40. 40. AN OUTPUT PROGRAM USING DEV C++ http://eglobiotraining.com
  41. 41. In this looping statement, I used “while” looping, and I choose to show MDASjust as an example for the program to run. http://eglobiotraining.com
  42. 42. This looping statement http://eglobiotraining.com
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  50. 50. http://eglobiotraining.com
  51. 51. Submitted to:Prof. Erwin GlobioSubmitted by:Tarun, April G. BM10203 http://eglobiotraining.com

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