Final requirement in programming niperos

Nisperos, Mark Anthony B.

http://eglobiotraining.com

Switch Case Statement
 In programming, a switch, case, select or inspect state
ment 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();
break;
void playgame() case 2: // Note the colon, not a semicolon
{ loadgame();
cout << "Play game called"; break;
} case 3: // Note the colon, not a semicolon
void loadgame() playmultiplayer();
{ break;
cout << "Load game called"; case 4: // Note the colon, not a semicolon
} cout<<"Thank you for playing!n";
void playmultiplayer() break;
{ default: // Note the colon, not a semicolon
cout << "Play multiplayer game called"; cout<<"Error, bad input, quittingn";
} break;
int main() }
{ cin.get();
int input; }
cout<<"1. Play gamen";
cout<<"2. Load gamen";
cout<<"3. Play multiplayern";
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.

Actual source code of program 3
#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;
}


output program 3


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.


Actual source code of program 4
#include <iostream> void welcome()
#include <stdlib.h> {
cout << "This program displays different messages
using namespace std; dependingn";
void welcome(); cout << "on which number is entered by the user.n";
int getInteger(); cout << "Pick a number between 1 and 6 to see whatn";
void displayResponse(int choice); cout << "the program will say.nn";
int main(int argc, char *argv[]) } // end of welcome function
{ // getInteger asks the user for a number between 1 and 6.
int choice; // declares the choice variable // The integer is returned to where the function was called.
welcome(); // This calls the welcome function int getInteger()
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
system("PAUSE"); response
return 0; return response; // sends back the response value
} // end main } // end getInteger function
// welcome function displays an opening message to // displayResponse function takes the int variable and uses
// explain the program to the user it

// 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";
// switch statement based on the choice variable break; // this ends the statements for case 5
switch (choice) // notice no semicolon case 6: // choice was the number 6
{ cout << "Six is divisible by two and three.nn";
case 1: // choice was the number 1 break; // this ends the statements for case 6
cout << "One is a lonely number and very useful in default: // used when choice falls out of the cases
math.nn"; covered above
break; // this ends the statements for case 1 cout << "You didn't pick a number between 1 and
case 2: // choice was the number 2 6.nn";
cout << "Two is the only even prime number.nn"; again = getInteger(); // gives the user another try
break; // this ends the statements for case 2 displayResponse(again); // recalls 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";
break; // this ends the statements for case 3 } // end displayResponse function
case 4: // choice was the number 4
cout << "Four square is a fun game to play, but four
squared is ";
cout << 4 * 4 << ".nn";
break; // this ends the statements for case 4


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.


Actual Source code of program 5
#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
cin >> response; // gets input from user and assigns it to response
system("PAUSE"); return response; // sends back the response value
return 0; } // end getChar function
} // end main // displayResponse function takes the char variable and uses it
// welcome function displays an opening message to // to determine which set of tasks will be performed.
// explain the program to the user 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
 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>

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();
}


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.


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Final requirement in programming niperos

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