Switch case and looping


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Switch case and looping

  1. 1. http://eglobiotraining.com/
  2. 2. What is computer program? is a sequence of instruction written to perform a specified task with a computer. A computer requires programs to function, typically executing the programs instructions in central processor. The program has an executable form that the computer can use directly to execute the instructions. The same program in its human-readable source code form, from which executable programs are derived (e.g., compiled), enables a programmer to study and develop its algorithms. http://eglobiotraining.com/
  3. 3.  Computer source code is often written by computer programmers. Source code is written in a programming language that usually follows one of two main paradigms: imperative programming or declarative programming. Source code may be converted into an executable file (sometimes called an executable program or a binary) by a compiler and later executed by a central processing unit. http://eglobiotraining.com/
  4. 4. Computer Programmer is a person who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst. http://eglobiotraining.com/
  5. 5.  Programmers are people who design the program of events that turns input data into output data. It has been proved that such a program of events can be designed using a structure composed of sequences, iterations and selections. Code is merely the way that the program is described. http://eglobiotraining.com/
  6. 6. Programming is the iterative process of writing or editing source code. Editing source code involves testing, analyzing, and refining, and sometimes coordinating with other programmers on a jointly developed program. A person who practices this skill is referred to as a computer programmer, software developer or coder. The sometimes lengthy process of computer programming is usually referred to as software development. The term software engineering is becoming popular as the process is seen as an engineering discipline. http://eglobiotraining.com/
  7. 7. Programming is instructing a computer to dosomething for you with the help of a programming language.The role of a programming language can be described in twoways: Technical: It is a means for instructing a Computer to perform Tasks Conceptual: It is a framework within which we organize our ideas about things and processes. http://eglobiotraining.com/
  8. 8.  A Programming Language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely. http://eglobiotraining.com/
  9. 9.  Programming language is usually split into the two components of syntax (form) and semantics(meaning). Some languages are defined by a specification document (for example, the C programming language is specified by an ISO Standard), while other languages, such as Perl 5 and earlier, have a dominant implementation that is used as a reference. http://eglobiotraining.com/
  10. 10.  A programming language is a computer language programmers use to develop applications, scripts, or other set of instructions for a computer to execute. Below is a listing of several different programming languages and scripting languages currently listed in our database. ALGOL FORTRAN Prolog Ada FoxPro Ruby AIML HDML SGML Assembly HTML Smalltalk BASIC Java SQL Batchfile JavaScript Tcl BCPL JCL True BASIC C LISP VHDL C# Live Script Visual Basic C++ LOGO Visual FoxPro COBOL Pascal WML CPL Perl WHTML D PHP XML DarkBASIC Pick dBASE http://eglobiotraining.com/
  11. 11. The most important aspect of programming is to analyze and adopt specific solution while solving any problem. This needs a programming approach that defines the modularity of program that one writes and how it is related to others in an application. http://eglobiotraining.com/
  12. 12. C++ is a statically typed, free-form, multi- paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. C++ is one of the most popular programming languages and is implemented on a wide variety of hardware and operating system platforms. C++ has greatly influenced many other popular programming languages, most notably C# and Java. Other successful languages such as Objective-C use a very different syntax and approach to adding classes to C. http://eglobiotraining.com/
  13. 13.  C++ is one of the most used programming languages in the world. Also known as "C with Classes". C++ is a general-purpose programming language with high-level and low-level capabilities. It is a statically typed, free-form, multi-paradigm, usually compiled language supporting procedural programming, data abstraction, object-oriented programming, and generic programming. http://eglobiotraining.com/
  14. 14. Switch Case In programming, a switch, case, select or inspect sta tement is a type of selection control mechanism that exists in most imperative programming languages such as Pascal, Ada, C/C++, C#, Java, and so on. The main reasons for using a switch include improving clarity, by reducing otherwise repetitive coding, and (if the heuristics permit) also offering the potential for faster execution through easier compiler optimization in many cases. http://eglobiotraining.com/
  15. 15.  The switch-case statement is a multi-way decision statement. Unlike the multiple decision statement that can be created using if-else, the switch statement evaluates the conditional expression and tests it against numerous constant values. http://eglobiotraining.com/
  16. 16. 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;}Switch case statements are a substitute for long if statements that compare a variable toseveral "integral" values ("integral" values are simply values that can be expressed as aninteger, such as the value of a char). The basic format for using switch case is outlinedbelow. The value of the variable given into switch is compared to the value following eachof the cases, and when one value matches the value of the variable, the computercontinues executing the program from that point. http://eglobiotraining.com/
  17. 17.  The condition of a switch statement is a value. The case says that if it has the value of whatever is after that case then do whatever follows the colon. The break is used to break out of the case statements. Break is a keyword that breaks out of the code block, usually surrounded by braces, which it is in. In this case, break prevents the program from falling through and executing the code in all the other case statements. An important thing to note about the switch statement is that the case values may only be constant integral expressions. http://eglobiotraining.com/
  18. 18. int a = 10; int b = 10;Sadly, it isnt legal to use case int c = 20; like this: switch ( a ) { case b: /* Code */ break; case c: /* Code */ break; default: /* Code */ break; } http://eglobiotraining.com/
  19. 19.  The default case is optional, but it is wise to include it as it handles any unexpected cases. It can be useful to put some kind of output to alert you to the code entering the default case if you dont expect it to. Switch statements serve as a simple way to write long if statements when the requirements are met. Often it can be used to process input from a user. http://eglobiotraining.com/
  20. 20. #include <iostream>using namespace std;void playgame(){ cout << "Play game called";}void loadgame() This is a sample} cout << "Load game called"; program, in which notvoid playmultiplayer(){ cout << "Play multiplayer game called"; all of the proper} functions are actuallyint main(){ int input; declared, but which cout<<"1. Play gamen"; cout<<"2. Load gamen"; shows how one would cout<<"3. Play multiplayern"; cout<<"4. Exitn"; use switch in a program. 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/
  21. 21.  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 try mentally putting in if statements for the case statements. Default simply skips out of the switch case construction and allows the program to terminate naturally. If you do not like that, 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. http://eglobiotraining.com/
  22. 22. LoopingIn computer programming, a loop is a sequence of instructions that is continually repeated until a certain condition is reached. Typically, a certain process is done, such as getting an item of data and changing it, and then some condition is checked such as whether a counter has reached a prescribed number. http://eglobiotraining.com/
  23. 23. If it hasnt, the next instruction in the sequence isan instruction to return to the first instruction inthe sequence and repeat the sequence. If thecondition has been reached, the next instruction"falls through" to the next sequential instructionor branches outside the loop. A loop is afundamental programming idea that is commonlyused in writing programs. http://eglobiotraining.com/
  24. 24. Loops are used to repeat a block of code. Being able tohave your program repeatedly execute a block of codeis one of the most basic but useful tasks inprogramming -- many programs or websites thatproduce extremely complex output (such as a messageboard) are really only executing a single task manytimes. (They may be executing a small number oftasks, but in principle, to produce a list of messagesonly requires repeating the operation of reading insome data and displaying it.) Now, think about whatthis means: a loop lets you write a very simplestatement to produce a significantly greater resultsimply by repetition. http://eglobiotraining.com/
  25. 25. One Caveat: before going further, you should understand the concept of C++s true and false, because it will be necessary when working with loops (the conditions are the same as with if statements).There are three types of loops: for While do..while http://eglobiotraining.com/
  26. 26. For A for loop allows a statement to be executed a specified number of times. http://eglobiotraining.com/
  27. 27. pseudo code  The for loop begins with a loop control variablefor (initial-value, final-value, increment) assigned a specific initialstatement-1 value. This control variable in then incremented (or decremented) by a specified amount eachExample: time around the loop until a specified terminatingfor (a = 3, a > 12, a = a + 2) value is reached at whichprint a time the statement following the loop is thenThis example will output 3 5 7 9 11. executed http://eglobiotraining.com/
  28. 28. While A while loop allows a statement to be executed until a given condition is met. If the condition is met prior to executing the loop then the loop will not be executed. As soon as the condition is met, execution continues with the statement following the loop. http://eglobiotraining.com/
  29. 29. Pseudo codewhile not conditionstatement-1 WHILE loops are very simple.Example:#include <iostream>using namespace std; // So we can see cout and endlint 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();} http://eglobiotraining.com/
  30. 30. DO..WHILEDO..WHILE loops are useful for things that want to loop at least once.In most computer programming languages, a do while loop, sometimes just called a do loop, is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. Note though that unlike most languages, Fortrans do loop is actually analogous to the for loop. http://eglobiotraining.com/
  31. 31. Pseudo code do { } while ( condition ); Example: Notice that the condition is#include <iostream> tested at the end of the block instead of theusing namespace std; beginning, so the block will be executed at least once. Ifint main() the condition is true, we Example: jump back to the beginning{ int x; of the block and execute it again. A do..while loop is x = 0; basically a reversed while do { loop. A while loop says // "Hello, world!" is printed at least one time "Loop while the condition // even though the condition is false is true, and execute this cout<<"Hello, world!n"; block of code", a do..while } while ( x != 0 ); loop says "Execute this cin.get(); block of code, and loop} while the condition is http://eglobiotraining.com/ true".
  32. 32. Codes and Explanations of the Programhave been tested http://eglobiotraining.com/
  33. 33. Switch Case http://eglobiotraining.com/
  34. 34. #include<stdio.h>#include<conio.h>main(){ int choice; float x,y; Switch case 1 printf("Enter the value of 1st:"); scanf("%f",&x); printf("Enter the value of 2nd :"); scanf("%f",&y); printf("1.Addn"); printf("2.Subtactn"); printf("3.Multificationn"); printf("4.Divisionn"); printf("nnnEnter your choice[1-4]: "); scanf("%d",&choice); switch(choice) { case 1: printf("THE result is :%f",x+y); break; case 2: printf("The result is :%f",x-y); break; case 3: printf("The result is :%f",x*y); break; case 4: printf("The result is :%f",x/y); break; default: printf("unknown"); } fflush(stdin); getchar(); } http://eglobiotraining.com/
  35. 35. #include <iostream>using namespace std;int main(){cout << "Enter a number between 1 and 5!" << endl; Switch case 2int 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");} http://eglobiotraining.com/
  36. 36. #include <iostream>using namespace std;int main(void){ char grade; cout << "Enter your grade: ";  Switch case 3 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/
  37. 37. #include <stdlib.h>#include <stdio.h>int main(void) { int n; printf("Please enter a number: ");  Switch case 4 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/
  38. 38. #include <iostream.h>using namespace std;int main(void)  Switch case 5 { 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; } } http://eglobiotraining.com/
  39. 39. Looping http://eglobiotraining.com/
  40. 40. #include <iostream> Looping 1using namespace std; // So the program can see cout andendlint main(){ // The loop goes while x < 10, and x increases by oneevery 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/
  41. 41. #include <iostream>#include <stdlib.h>using namespace std;int main(){int x, score, tnum_stud, t_score, ave_score;char student_name[20];tnum_stud = 0, t_score = 0, ave_score = 0;cout<< "Enter student name: "; Looping 2cin>>student_name;cout<< "Enter score: ";cin>> score;t_score = t_score + score;for (x = 1; x <= 4; x++){cout<< "Enter score: ";cin>> score;t_score = t_score + score;}tnum_stud = x++;ave_score = t_score/tnum_stud;cout<< "Total no. of students: "<<tnum_stud<<endl;cout<< "Total score: " <<t_score<<endl;cout<< "Total average score: "<<ave_score<<endl;tnum_stud = 0, t_score = 0, ave_score = 0;cout<< "nnn";system ("PAUSE");return 0;} http://eglobiotraining.com/
  42. 42. #include <iostream.h> Looping 3int main(){ int x = 0; do { cout<<"This will loop 2 timesand stop."<<endl; }while(x != 1);return 0;} http://eglobiotraining.com/
  43. 43. // custom countdown using while#include <iostream>using namespace std;int main (){ Looping 4 int n; cout << "Enter the starting number> "; cin >> n; while (n>0) { cout << n << ", "; --n; } cout << "FIRE!n"; return 0;} http://eglobiotraining.com/
  44. 44. #include <iostream.h>int main(){ int x; while (x != 0) Looping 5 { cout<<"What would youlike to do? (0 - Quit 1 - Stay):"<<endl; cin>>x; }return 0;} http://eglobiotraining.com/
  45. 45. An outputprogram using Dev C++ http://eglobiotraining.com/
  46. 46. Switch case 1  Take a look at the placement of the curly brackets and how the indentations are placed. This is all done to make reading easier and to make less mistakes in large programs. http://eglobiotraining.com/
  47. 47. Switch case 2 If you use an “if statement” in an “if statement” it is called nesting. Nesting ”if statements” can make a program very complex, but sometimes there is no other way. So use it wisely. http://eglobiotraining.com/
  48. 48. Switch case 3 The if statement can be used to test conditions so that we can alter the flow of a program. In other words: if a specific statement is true, execute some instructions. If not true, execute these instructions. http://eglobiotraining.com/
  49. 49. The programs end functionality has not changed, only the method of implementation in the C++ source code. The program reads user input from the keyboard until the return key is pressed. After the user inputs a number, that value is stored into the integer variable "n". The variable "n" is then tested by a switch statement. If the user inputs the number 1, then "n is equal to 1!" is printed as shown below. Switch case 4 http://eglobiotraining.com/
  50. 50. In the above Control Structure example the "switch" statement is used to find the day of the week from the integer input got from the user. http://eglobiotraining.com/ Switch case 5
  51. 51. 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/ Looping 1
  52. 52. If the “default” block is last block in your switch order, then it isn’t necessary to state break next to it.Consequence of falling through case labels in lack of break order is that the same collection of orders is executed for more different case labels. http://eglobiotraining.com/ Looping 2
  53. 53. 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/ Looping 3
  54. 54. When the program starts the user is prompted to insert a starting number for the countdown. Then the while loop begins, if the value entered by the user fulfills the condition n>0 (that n is greater than zero) the block that follows the condition will be executed and repeated while the condition (n>0) remains being true. http://eglobiotraining.com/ Looping 4
  55. 55. The easiest way to think of the loop is that when it reaches thebrace at the end it jumps back up to the beginning of theloop, which checks the condition again and decides whether torepeat the block another time, or stop and move to the nextstatement after the block. http://eglobiotraining.com/ Looping 5
  56. 56. Submitted to:Prof. Erwin Globio http://eglobiotraining.com/Submitted by:Hidalgo, Patricia M.BM10203 http://eglobiotraining.com/ 56