Final requirement

Switch Case and
Looping Statements

Fae Loise Salosagcol
FM10205 – Fundamentals of Programming :)
Far Eastern University

http://eglobiotraining.com

Switch Statements :)


Switch Case
The switch/case statement in programming usually is
used to replace multiple if/else statements.
The general syntax is:


Now, let's see it working: Let's say that we want to write a program
that will ask for a number between 1 and 5, and it will write out
the number in text format (1 = one, 2 = two, 3 = three ....).
Using the if/else if statements in programming it will look like in
the below example:


And using the switch/case break;
statement: In programming, The break is used to break
out from the switch/case statement.
Without break the program will execute all
the code after the selected one. For
example, if we don't use breaks in the
above code, and the user inputs 3, the
program will show:threefourfive3 is not
between 1 and 5! instead of three

default:
The default case in programming is
optional, this is executed when none of the
previous cases are executed or when you
forget the break;.

Note: The cases (including the default case)
are followed by a colon, not semicolon!
Note: This is very important in
Programming! A variable can't be used as
possible value of a case statement! Example
of how NOT to do:

int myvariable = 1;
switch (x){
case myvariable: //this is NOT valid
//code to execute
}

Switch Statement
In programming, Switch Statement type of
conditional statement. It allows users when there
are many options available and only one option
should be executed.

Instead of using a series of if...else if statements in
programming we can use switch statement. The
switch statement controls a program by executing
statements. These statements depend on the value
of the expression. In programming, the value of the
expression should be integer or character data type.
It uses single expression for multiple options. It
cannot replace the nested if…else completely but it
can be helpful for users.

The value of the switch expression is compared with
each of the given case. When a match found then it
execute the statements. Otherwise it does not
execute the statements and then the default
statements are executed. In programming,
break statement is used to end a particular case. If
we do not use a break statement in programming
then there will be a problem that the remaining
cases will execute if they match the expression of
the switch including the default statement.


Switch Statement
In programming, the switch
statement is almost the same
as an “if statement”. The
switch statement can have
many conditions. You start the
switch statement with a
condition in programming. If
one of the variable equals the
condition, the instructions are
executed. It is also possible to
add a default in programming.
If none of the variable equals
the condition the default will
be executed. See the
example:

Note: break is used to exit the switch.


Switch Statement

In this example, a break statement in programming follows each statement of
the switch body. The break statement forces an exit from the statement body
after one statement is executed. The final break statement is not strictly
necessary, since control passes out of the body at the end of the compound
statement, but it is included for consistency.


Switch Statement


Switch Case
In programming, the break
statement interrupts the flow
of control. We have seen in
switch statement that when a
true case is found, the flow of
control goes through every
statement downward. We
want that only statements of
true case should be executed
and the remaining should be
skipped. For this purpose, we
use the break statement. The
break statement is necessary
in switch structure, without it
in programming the switch
structure becomes illogic. As
without it all the statement
will execute after first match
case is found.


Explanation:
Expression shall be an expression, convertible to an integer value.

All constant_expressions in programming shall be constant
expressions, convertible to an integer value, which is unique within
this switch statement

If the expression evaluates to a value, equal to the value of one of
the defined constant_expressioni, the statement (if present) and all
subsequent statements (except default_statement, if present) are
executed. If the value of the expression does not match any of
the constant_expressions, the default_statement is executed if
present.

It is useful to note, that if the execution in programming of
subsequent statements is undesirable, the break statement can be
used. In that case the execution of the switch statement terminates.


Loop Statements :)
different types of Looping statements
such as For, While, and Do


While Loop The for loop is a very flexible C/C++ construct.
In programming, we also can use the count
down, decrementing the counter variable
instead of incrementing.

We can use counter other than 1, The
initialization expression can be omitted if the
test variable has been initialized previously in
the program. However the semicolon must
still be used in the statement. The
initialization expression need not be an actual
initialization, it can be any valid C/C++
expression, the expression is executed once
when the for statement is first reached. he
incremented expression can be omitted as long
as the counter variable is updated within the
body of the for statement.

The semicolon still must be included. The test
expression that terminates the loop can be any
C/C++ expression in programming. As long as
it evaluates as true (non zero),
the for statement continues to execute.
Logical operators can be used to construct
complex test expressions.
An expression can be created by separating
two sub expressions with the comma
operator, and are evaluated (in left-to-right
order), and the entire expression evaluates to
the value of the right sub expression. Each
part of the for statement can be made to
perform multiple duties.


While Loop Loops in programming have as objective
to repeat a statement a certain number
of times or while a condition is fulfilled.
The while loop.
Its format is:
while (expression) statement and its
function in programming is simply to
repeat statement while expression is
true. For example, we are going to make a
program to count down using a while loop:

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 be
greater than 0 ),the block of instructions
that follows will execute indefinite times
while the condition (n>0) remains being
true.

All the process in the program above can be interpreted according to the following
script: beginning in main: (1). User assigns a value to n. (2). The while instruction
checks if (n>0). At this point there are two possibilities:
1st. true: execute statement (step 3,) 2nd. false: jump statement. The program
follows in step 5.. (3). Execute statement: cout << n << ", "; --n; (prints out n on screen
and decreases n by 1). (4). End of block. Return Automatically to step 2. (5). Continue
the program after the block: print out FIRE! and end of program.

Format:
Do-While Loop do statement while condition; Its
functionality in programming is exactly
the same as the while loop except
that condition in the do-while is
evaluated after the execution
of statement instead of before,
granting at least one execution
of statement even if condition is
never fulfilled. For example, the
following program echoes any number
you enter until you enter 0.

The do-while loop in programming is
usually used when the condition that has
the relative output
to determine its end is determined
within the loop statement, like in the
Enter number (0 to end): 12345
previous case, where the user input
You entered:12345
within the block of instructions is what
Enter number (0 to end): 160277
determines the end of the loop. If you
You entered: 160277 never enter the 0 value in the previous
Enter number (0 to end): 0 example the loop will never end.
You entered: 0


Its format is:
For Loop for (initialization; condition; increase) state
ment; and its main function is to
repeat statement while condition remains
true, like the while loop. But in
addition, for provides places to specify
an initialization instruction and
an increase instruction. So this loop in
programming is specially designed to perform
a repetitive action with a counter. It works
the following way:

1, initialization is executed. Generally in
programming it is a initial value setting for a
counter variable. This is executed only once.
2, condition is checked, if it is true the loop
continues, otherwise the loop finishes
and statement is skipped. 3, statement is
executed. As usual, it can be either a single
instruction or a block of instructions enclosed
within curly brackets { }. 4, finally, whatever
is specified in the increase field is executed
and the loop gets back to step 2. > Here is an
example of countdown using a for loop.

The initialization and increase fields are optional. They can be avoided but not the
semicolon signs among them. Thus, for example we could write: for (;n<10;) if we
want to specify no initialization neither increase; or for (;n<10;n++) if we want to
include an increase field but not an initialization. Optionally, using the comma
operator (,) we can specify more than one instruction in any of the fields included in
a for loop, like in initialization, for example. The comma operator (,) in
programming is an instruction separator, it serves to separate more than one
instruction where only one instruction is generally expected.

For Loop
FOR - for loops are the most useful type. The syntax for a for loop is

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 in programming 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. In
programming, if the condition is empty, it is evaluated as true and the loop
will repeat until something else stops it.


For Loop

This program is a very simple example in programming 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://www.slideshare.net/fayesalosagcol


Submitted to: Prof. Erwin M. Globio


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