chapter 2 decesion making statements dk mamonai 09ce37

8/6/2019 Chapter 2 Decesion making statements Dk Mamonai 09CE37

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Test Expression

Test Expression

OBJECT: TOBECOMEFAMILIARWITH DECISIONMAKINGSTATEMENTS.

DECISIONMAKINGSTATEMENTS

Decision making statements are the statements which take the decisions to make the

conditions satisfied and execute their body. If the condition is satisfied (True) then thestatement will cause its body to be executed and if the condition is not satisfied (False)then the control will be transferred to the next condition or to the first statement afterthe body of the conditional statement. There are three types of decision making

statement also known as conditional statements. These are so called conditionalstatements because they depend on certain conditions. They are,

1) The if Statement

2) The if-else Statement

3) The switch Statement

1) The if Statement

It is the simplest decision making/conditional statement. The if statement contains thekeyword ifwhich is predefined in C++ followed by the condition in the parentheses ()with some relational and logical operators. If the condition is satisfied then the body ofthe if statement will be executed else the control will be transferred to the first existing

statement after the if statement. If the body of the if statement contains only singlestatement then you dont have to enclose that statement in the braces but in case of

multiple statements you should enclose the block of code in the curly braces. Thesyntax of the if statement is given below;

if (a>b && a>c)

statement; Single Statement if body

if (a>b && a>c)

{

statement;

statement; Multiple Statement if body

statement;

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}

FLOWCHARTOFIF STATEMENT

Program (If.cpp)

#include

#include

void main()

{

int Age1=20, Age2=15, Age3=7;

if(Age1>Age2&&Age1>Age3)

{

cout


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Test Expression

Test Expression

2) The if-else Statement

The if-else statement is another decision making statement. The if-else statementcontains the keywords if and else which are predefined in C++. The condition iscontained in theparentheses () after the keyword if. If the condition is satisfied then the

block of code after the keyword ifis executed while if the condition is not satisfied thenthe control is transferred to the else and the block of code contained after it is executed.

If you want to execute the single statement if the condition is either satisfied or not thenyou dont have to enclose it in the curly braces but if you want to execute certain block

of code (multiple statements) then you have to enclose the block of code in the curlybraces. The syntax of the if-else statement is given below;

if (a>b && a>c)

statement; Single Statement if body

else

statement; Single Statement else body

if (a>b && a>c)

{

statement;

statement; Multiple Statement if body

statement;

}

else{

statement;

statement; Multiple Statement else body

statement;


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}

FLOWCHARTOFIF-ELSE STATEMENT

Program (IfElse.cpp)

#include

#include

void main()

{

int num1=100, num2=50;

if(num1>num2)

{

cout


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Integer or character variable

Note: no semicolon here

Integer or character constant

First case body

Causes exit from switch

Second case body

Third case body

Default case body

Note: no semicolon here

3) The switch Statement

The switch statement is also the decision making statement like if statementand if-elsestatement. The switch statement is used when the bunch of decisions depend on the

same variable. It works as if and if-else statements but it is some what clearer andeasily understandable at glance. The switch statement starts with the keyword switch

(lower case) followed by the variable in the parentheses (). The switch statement takesthe decision according to the values of the variable in the parenthesis. The whole body

of the switch statement is enclosed by curly braces. Then the switch statement matchesthe values of the variable with the cases in its body. The keyword case followed by thechoice and the colon makes the block of code below it to be executed if the value of theswitch variable matches with the choice in the case. You can give multiple cases in the

switch statement and the switch statement will try to match the value of the variablewith the cases and if no case is matched the control is returned to the default. The key

word defaultfollowed by the colon causes the block of code below it to be executed if

the switch statement does not match any of the case. The breakstatement is used afterthe block of code in each case, which causes the control to be transferred out of theswitch statement when ever the case executes its block of code. The syntax of the

switch statement is given below;

switch (ch)

{

case 1:

statement;statement;

break;

case 2:

statement;

statement;

break;

case 3:

statement;statement;

break;

default:

statement;

statement;

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True

True

True

}

FLOWCHARTOFSWITCHSTATEMENT

Switch

variableequals 1st

case constant

1st case body

Exit

False

Switchvariable

equals 2ndcase constant

Switchvariable

equals 3rdcase constant

2nd case body

3rd case body

Default body

False

False

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Program (Switch.cpp)

#include

#include

void main()

{

int a, b;

char ch;

couta;

coutb;

cout


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EXERCISE

1) Write a program that determines the year entered by user is leap year or not?

2) Write a program which gives the following output

Enter age>>

And prints the following:

If Age is greater than 45 then prints the message You are old stay at home and wait

for call

If Age is greater than 30 and less than 45 then prints Hey! man enjoy your life withyour kids

If Age is greater than 20 and less than 30 then prints Cool! have a search for yourbest suit

If Age is greater than 10 and less than 20 then prints Work hard! Your days to

study

If Age is less than 10 then prints the message Oh! Kid your days to cry

Use if-else statement.

3) Write the above program #02 by using the switch statement?

4) Develop a C++ program which will compute the power dissipation of a resistor,when the user inputs current value and the resistance. Program warns the user if

power dissipation is above 1 watt. The power dissipation is measured by P=I2R.

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EXERCISESOLUTIONS

===================================================

Program #01

#include

#include

void main()

{

int year;

coutyear;

if(year%4==0)

cout


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else if(Age>30&&Age


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{

case 1:

cout


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===================================================

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chapter 2 decesion making statements dk mamonai 09ce37

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