Final requirement in programming

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FINAL REQUIREMENT IN
PROGRAMMING
Del Rosario, Trisha Maxine A.

SWITCH CASE AND LOOPING

SWITCH CASE STATEMENT
 In programming,
a switch, case, select or inspect statement is a type

of selection control mechanism that exists in
most imperative programming languages such
as Pascal, C/C++, C#, Java, and so on.
 It is also included in several other types of
languages.
 Its purpose is to allow the value of a variable or
expression to control the flow of program execution
via a multiway branch (or "goto", one of several
labels).

SWITCH CASE
 The main reasons for using a switch in programming
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.
 It is a substitute for long if statements that compare a
variable to several "integral" values ("integral" values are
simply values that can be expressed as an integer, such
as the value of a char).
 In computer programming, 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.

THE BASIC FORMAT FOR USING SWITCH CASE
IS OUTLINED BELOW.
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
 In computer programming, 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 as one of

the language used in programming 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.
 It can be useful to put some kind of output to alert you to the
code entering the default case if you don't expect it to. Switch
statements serve as a simple way to write long if statements
when the requirements of programming are met. Often it can
be used to process input from a user.

ACTUAL SOURCE CODE OF SWITCH CASE
#include <iostream> switch ( input ) {
case 1: // Note the colon, not a semicolon
using namespace std;
playgame();
void playgame() break;

{ case 2: // Note the colon, not a semicolon
cout << "Play game called"; loadgame();
}
break;
void loadgame()
{
case 3: // Note the colon, not a semicolon
cout << "Load game called"; playmultiplayer();
} break;
void playmultiplayer() case 4: // Note the colon, not a semicolon
{
cout<<"Thank you for playing!n";
cout << "Play multiplayer game called";
}
break;
int main() default: // Note the colon, not a semicolon
{ cout<<"Error, bad input, quittingn";
int input;
break;
cout<<"1. Play gamen";
}
cout<<"2. Load gamen";
cout<<"3. Play multiplayern"; cin.get();
cout<<"4. Exitn"; }
cout<<"Selection: ";
cin>> input;

SCREEN SHOTS OF OUTPUT PROGRAM 1


EXPLANATION
 In this program, the user will select if he wants to
play, load, play multiplayer or close the game based

on the number indicated in the output program of
the programming software.

ACTUAL SOURCE CODE OF PROGRAM 2
#include <stdlib.h> case 3:
#include <stdio.h> {
printf("n is equal to 3!n");
int main(void) { break;

int n; }
printf("Please enter a number: "); default:
scanf("%d", &n); {
switch (n) printf("n isn't equal to 1, 2, or 3.n");
{ break;
case 1: }
{ }
printf("n is equal to 1!n"); system("PAUSE");
break; return 0;
} }
case 2:
{
printf("n is equal to 2!n");
break;
}

EXPLANATION
 #include <iostream>
- This tells the compiler to include files in using dev c++
of programming.

 #include <stdlib.h>
- This tells the compiler to include files.
 int main(int argc, char *argv[])
- This starts the main function use in programming.
 This 2nd example program that I did for the requirement
in programming will ask the user to select a number.
After entering the number, the programming software
which is the dev c++ program will print if the entered
number is equal to 1, 2 or 3. It will print different things
on the screen depending on which number the user
chose.

#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;
}

3
OUTPUT PROGRAM

EXPLANATION

 This 3rd program of programming will ask the user
to select a number between 1 and 5. Then the

program will print different things on the screen
depending on which number the user chose. The
switch statement can be very helpful in handling
multiple choices in programming.

#include <iostream> void welcome()
#include <stdlib.h> {
cout << "This program displays different messages
dependingn";
cout << "on which number is entered by the user.n";

void welcome();
cout << "Pick a number between 1 and 6 to see whatn";
int getInteger();
cout << "the program will say.nn";
void displayResponse(int choice);
} // end of welcome function
int main(int argc, char *argv[])
// getInteger asks the user for a number between 1 and 6.
{
// The integer is returned to where the function was called.
int choice; // declares the choice variable
int getInteger()
welcome(); // This calls the welcome function
{
choice = getInteger(); // calls getInteger and receives the
value for choice int response; // declares variable called response
displayResponse(choice); // passes choice to cout << "Please type a number between 1 and 6: "; //
displayResponse function prompt for number
cin >> response; // gets input from user and assigns it to
response
system("PAUSE");
return response; // sends back the response value
return 0;
} // end getInteger function
} // end main
// displayResponse function takes the int variable and uses it
// welcome function displays an opening message to
// explain the program to the user
// to determine which set of tasks will be performed.
void displayResponse(int choice)

SOURCE CODE
{ case 5: // choice was the number 5
int again; cout << "Counting by fives is fun. Five, Ten, Fifteen,
Twenty...nn";
break; // this ends the statements for case 5
// switch statement based on the choice variable

case 6: // choice was the number 6
switch (choice) // notice no semicolon
cout << "Six is divisible by two and three.nn";
{
default: // used when choice falls out of the cases
cout << "One is a lonely number and very useful in covered above
math.nn";
cout << "You didn't pick a number between 1 and
break; // this ends the statements for case 1 6.nn";
case 2: // choice was the number 2 again = getInteger(); // gives the user another try
cout << "Two is the only even prime number.nn"; displayResponse(again); // recalls
break; // this ends the statements for case 2 displayResponse with new number
case 3: // choice was the number 3 break;
cout << "Three is a crowd and also a prime } // end of switch statement
number.nn"; } // end displayResponse function
cout << "Four square is a fun game to play, but four
squared is ";
cout << 4 * 4 << ".nn";

EXPLANATION

 This is the 4th example that I included in my final
requirement in programming. This program displays

different messages depending on which number is
entered by the user. The user will be asked to pick
a number between 1 and 6 to see what the program
will say. Then, after the user enter the number, the
programming software will print if it is an even or
odd number.

#include <iostream> void welcome()
#include <stdlib.h> {
cout << "This program displays different messages dependingn";
using namespace std; cout << "on which letter is entered by the user.n";
void welcome(); cout << "Pick a letter a, b or c to see whatn";

char getChar(); cout << "the program will say.nn";
void displayResponse(char choice); } // end of welcome function
int main(int argc, char *argv[]) // getChar asks the user for a letter a, b or c.
{ // The character is returned to where the function was called.
char choice; // declares the choice variable char getChar()
welcome(); // This calls the welcome function {
choice = getChar(); // calls getChar and returns the value for choice char response; // declares variable called response
displayResponse(choice); // passes choice to displayResponse function
cout << "Please type a letter a, b or c: "; // prompt for letter
system("PAUSE"); cin >> response; // gets input from user and assigns it to response
return 0; return response; // sends back the response value
} // end main } // end getChar function
// welcome function displays an opening message to // displayResponse function takes the char variable and uses it
// explain the program to the user // to determine which set of tasks will be performed.
void displayResponse(char choice)

SOURCE CODE
{
char again;

// switch statement based on the choice variable
switch (choice) // notice no semicolon

{
case 'A': // choice was the letter A
case 'a': // choice was the letter a
cout << "A is for apple.nn";
break; // this ends the statements for case A/a
case 'B': // choice was the letter b
case 'b': // choice was the letter b
cout << "B is for baseball.nn";
break; // this ends the statements for case B/b
case 'C': // choice was the letter C
case 'c': // choice was the letter c
cout << "C is for cat.nn";
break; // this ends the statements for case C/c
default: // used when choice falls out of the cases covered above
cout << "You didn't pick a letter a, b or c.nn";
again = getChar(); // gives the user another try
displayResponse(again); // recalls displayResponse with new character
break;
} // end of switch statement
} // end displayResponse function

SCREENSHOTS OF OUTPUT PROGRAM 5


EXPLANATION
 The final program of the requirement in
programming project displays different messages

depending on which letter is entered by the user.
The user will be asked to pick a letter a, b or c to
see what the program will say. Then, after the user
enter the number, the programming software which
is the dev c++ will print if it is an even or odd
number.

LOOPING STATEMENT

LOOPING STATEMENT
 In computer programming, a loop is a sequence
of instructions that is continually repeated until a certain
condition is reached.

 Typically, a certain process in programming 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.
 If it hasn't, the next instruction used in programming in
the sequence is an instruction to return to the first
instruction in the sequence and repeat the sequence. If
the condition has been reached, the next instruction
"falls through" to the next sequential instruction or
branches outside the loop.

 A loop is a fundamental programming idea that is
commonly used in writing programs.
 In object-oriented programming language, whenever a
block of statements has to be repeated a certain number
of times or repeated until a condition becomes satisfied,
the concept of looping is used.

 Loops are used to repeat a block of code. Being able to
have your program repeatedly execute a block of code
is one of the most basic but useful tasks in
programming.
 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, and do..while.
Each of them has their specific uses.

 The following commands used in C++ for achieving
looping:

 for loop
 while loop
 do-while loop

FOR LOOP
FOR - for loops are the most useful type in programming.
 The syntax for a for loop is

for ( variable initialization; condition; variable update ) {

Code to execute while the condition is true
}

 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 possible to do things like x++, x = x + 10, or even x =
random ( 5 ), and if you really wanted to, you could call other functions that do
nothing to the variable but still have a useful effect on the code.
 Notice 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. This is one of the important factors of a
programming language.

SOURCE CODE
#include <stdio.h>

int main()

{
int x;
/* The loop goes while x < 10, and x increases by one every
loop*/
for ( 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. */
printf( "%dn", x );
}
getchar();
}

SCREENSHOTS

EXPLANATION
 The variable initialization used in programming 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
possible to do things like x++, x = x + 10, or even x =
random ( 5 ), and if you really wanted to, you could call
other functions that do nothing to the variable but still
have a useful effect on the code. Notice 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 in programming is empty, it is
evaluated as true and the loop will repeat until
something else stops it.

SOURCE CODE
#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();
}

EXPLANATION

 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
of a programming language is incremented after the
code in the loop is run for the first time.

WHILE LOOP
 WHILE - WHILE loops are very simple. 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 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.

SOURCE CODE
#include <iostream>

using namespace std; // So we can see cout and endl

int main()
{
int x = 0; // Don't 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();
}

EXPLANATION

 This was another simple example, but it is longer
than the above FOR loop. 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.

DO-WHILE LOOP
DO..WHILE - DO..WHILE loops are useful for things in
programming that want to loop once. The structure is

do {
} while ( condition );

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".

SOURCE CODE
#include <iostream>


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();
}

SCREEN SHOTS

EXPLANATION

 In this example, once you compile and run the
source codes you did, the programming software
will print “Hello, world!” even though the condition is

false.

EXPLANATION

 Keep in mind that you must include a trailing semi-
colon after the while in the above example. A

common error in programming 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.

 URL :

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SUBMITTED TO:
PROF. ERWIN M GLOBIO
http://eglobiotraining.com/

THANK YOU!

Final requirement in programming

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