Jangsehyun final requirement

PROGRAMMING

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Switch case
Looping


 In programming, a switch, case, select or inspect stat
ement is a type of selection control mechanism that exis
ts in most imperative programming languages such a
s Pascal, Ada, C/C++, C#, Java, and so on. It is also inc
luded in several other types of Programming languages.
Its purpose is to allow the value of a variable or express
ion to control the flow of program execution via a multw
ay branch (or "go to", one of several labels). The main r
easons for using a switch include improving clarity, by r
educing otherwise repetitive coding, and (if the heuristic
s permit) also offering the potential for faster execution t
hrough easier compiler optimization in many cases.


 Switch case statements are 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). The basic format for using the s
witch case in the programming is outlined below. The value of
the variable given into switch is compared to the value followi
ng each of the cases, and when one value matches the value
of the variable, the computer continues executing the program
from that point.
 The switch-case statement is a multi-way decision statement
. Unlike the multiple decision statement that can be created us
ing if-else, the switch statement evaluates the conditional exp
ression and tests it against numerous constant values. The br
anch corresponding to the value that the expression matches i
s taken during execution.


 Switch is used to choose a fragment of template d
epending on the value of an expression
 This has a similar function as the If condition - but i
t is more useful in situations when there is many p
ossible values for the variable. Switch will evaluate
one of several statements, depending on the value
of a given variable. If no given value matches the v
ariable, the default statement is executed.
 The value of the expressions in a switch-case stat
ement must be an ordinal type i.e. integer, char, sh
ort, long, etc. Float and double are not allowed.


#include <iostream> // switch statement based on the choice variable
#include <stdlib.h>
using namespace std;
switch (choice) // notice no semicolon
void welcome(); {
char getChar(); case 'A': // choice was the letter A
void displayResponse(char choice); case 'a': // choice was the letter a
int main(int argc, char *argv[])
{
cout << "your awesome dude.nn";
char choice; // declares the choice variable break; // this ends the statements for case A/a
welcome(); // This calls the welcome function case 'B': // choice was the letter b
choice = getChar(); // calls getChar and returns the value for choice case 'b': // choice was the letter b
displayResponse(choice); // passes choice to displayResponse function
cout << "you will find your lovelife.nn";
system("PAUSE"); break; // this ends the statements for case B/b
return 0; case 'C': // choice was the letter C
} // end main case 'c': // choice was the letter c
// welcome function displays an opening message to
// explain the program to the user
cout << "your will won the lottery.nn";
void welcome() break; // this ends the statements for case C/c
{ case 'D': // choice was the letter D
cout << "This program displays different messages dependingn"; case 'd': // choice was the letter d
cout << "on which letter is entered by the user.n";
cout << "Pick a letter a, b, c or d to see whatn";
cout << "your so ugly!!.nn";
cout << "the program will say.nn"; break; // this ends the statements for case D/d
} // end of welcome function default: // used when choice falls out of the cases
// getChar asks the user for a letter a, b or c. covered above
// The character is returned to where the function was called. cout << "You didn't pick a letter a, b or c.nn";
char getChar()
{
again = getChar(); // gives the user another try
char response; // declares variable called response displayResponse(again); // recalls
cout << "Please type a letter a, b, c and d: "; // prompt for letter displayResponse with new character
cin >> response; // gets input from user and assigns it to response break;
return response; // sends back the response value } // end of switch statement
} // end getChar function
// displayResponse function takes the char variable and uses it
} // end displayResponse function
// to determine which set of tasks will be performed.
void displayResponse(char choice)
{
char again;


There may be a situation when you need to execute a block
of code several number of times. In general statements are
executed sequentially: The first statement in a function is
executed first, followed by the second, and so on.

Programming languages provide various control structures
that allow for more complicated execution paths.
A loop statement allows us to execute a statement or group
of statements multiple times and following is the general from
of a loop statement in most of the programming languages.


C++ programming language provides
following types of loop to handle
looping requirements:

WHILE DO
FOR WHILE
LOOP
LOOP LOOP


 A for loop is a repetition control structure that
allows you to efficiently write a loop that need
s to execute a specific number of times.
 The statements in the for loop repeat continu
ously for a specific number of times. The wh
ile and do-while loops repeat until a certain c
ondition is met. The for loop repeats until a s
pecific count is met. Use a for loop when the
number of repetition is know, or can be suppli
ed by the user.


#include <iostream> }
#include <cmath>
using namespace std; cout <<"nSeconds
falling distancen";
cout <<"---------------------------------------n";
//prototype
int fallingdistance(); for ( count = 1; count <= time; count++)
{
//main function distance = .5 * 9.8 *
int main() pow(time, 2.0);
cout << count << "
{ " << distance <<" meters"<< endl;
int count = 1 ;
int time; }
double distance ; system ("pause");
cout << "Please enter time in 1 return 0;
through 10 seconds.nn"; }
// falling distance function for a return value in seconds
transfer to time
time = fallingdistance(); int fallingdistance ()
{
while ( time < 1 || time > 10) int seconds;
{ cout << "Must enter between 1 and cin >> seconds;
10 seconds, please re-enter.n"; return seconds;
}
time = fallingdistance(); http://eglobiotraining.com

 The while loop allows programs to repeat
a statement or series of statements, over a
nd over, as long as a certain test condition
is true.
 The while loop can be used if you don’t kn
ow how many times a loop must run.
 A while loop statement repeatedly execute
s a target statement as long as a given co
ndition is true.


#include <iostream.h>

int main(void) {
int x = 0;
int y = 0;
bool validNumber = false;

while (validNumber == false) {
cout << "Please enter an integer between 1 and 10: ";
cin >> x;
cout << "You entered: " << x << endl << endl;

if ((x < 1) || (x > 10)) {
cout << "Your value for x is not between 1 and 10!"
<< endl;
cout << "Please re-enter the number!" << endl << endl;
}
else
validNumber = true;
}

cout << "Thank you for entering a valid number!" << endl;

return 0;
 }

 In most computer programming languages, a do while
loop, sometimes just called a while loop, is a control f
low statement that allows code to be executed once b
ased on a given Boolean condition.
 The do while construct consists of a process symbol a
nd a condition. First, the code within the block is execu
ted, and then the condition is evaluated. If the conditio
n is true the code within the block is executed again. T
his repeats until the condition becomes false. Because
do while loops check the condition after the block is ex
ecuted, the control structure is often also known as a p
ost-test loop. Contrast with the while loop, which test
s the condition before the code within the block is exec
uted.


 Unlike for and while loops, which test the loop co
ndition at the top of the loop, the do...while loop c
hecks its condition at the bottom of the loop.
 A do...while loop is similar to a while loop, except
that a do...while loop is guaranteed to execute at l
east one time.
 The do-while loop is similar to the while loop, exc
ept that the test condition occurs at the end of the
loop. Having the test condition at the end, guarant
ees that the body of the loop always executes at le
ast one time.


 #include <iostream>
 using namespace std;
 main()
 { int num1, num2;
 char again = 'y';

 while (again == 'y' || again == 'Y') {
 cout << "Enter a number: ";
 cin >> num1;
 cout << "Enter another number: ";
 cin >> num2;
 cout << "Their sum is " << (num1 + num2) << endl;
 cout << "Do you want to do this again? ";
 cin >> again; }
 return 0;
 }


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