Post on 14-Apr-2018
transcript
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Three control structures
selection/decision structures:- checks the
given condition and then execute its sub-
block.
if, ifelse,nested if, ladder if, switch
Repetition/loop structures:- statements
which are repeatedly executed for certain no
of times.
while, dowhile, for
Jumping statements:-goto,break,continue
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A simple ifstructure is called a single-selectionstructure because it either selects or ignores asingle action.
The if / else structure is called a double-selection structure because it selects betweentwo different actions.
Nested if / else structures test for multiple cases
by placing if / else structures inside other if /else structures.
The ladder if /else ifstructure test for multiplecases by placing different conditions in else if.
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Syntax:- if(condition)
{
------------------;
-------------------;
}
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include
#include
void main()
{
int age;
clrscr();
Coutage;
if(age>17){
Cout
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Syntax:- if(condition){
-----------------;
-------------------;
}
else
{
-----------------;
-------------------;}
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#include
#include
void main(){
int age;
clrscr();
Coutage;
if(age>17)
{
Cout
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Syntax:- if(condition)
{
If(){
}
Else
{
}
}
else
{
If()
{
}
Else
{
}
}
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Void main()
{
Int a=10,b=20,c=30;
If(a>b)
{
If(a>c)
{
cout
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Syntax:-
if (cond1)
{
statement1;
}
else if (cond2)
{
statement2;
}
else if (cond n)
{statement n;
}
else
statement;
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if ( studentGrade >= 90 )
cout = 80 )cout = 70 )
cout = 60 )
cout
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Compound statement Also called a block Set of statements within a pair of braces Used to include multiple statements in an if body
Example if ( studentGrade >= 60 )
cout
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Similar to if statements
Can list any number of branches
Used in place of nested if statements
Avoids confusion of deeply nested ifsMultiple way branch statement
Used for multiple selections
Tests a variable or expression
Compared against constant integral expressions to
decide on action to take
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Syntax:-switch (expression) {
case value1:statement1;
break;case value2:
statement2;break;
case valuen:statementn;break;
default:statement;}
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switch statement
Controlling expression
Expression in parentheses after keyword switch
case labels Compared with the controlling expression
Statements following the matching case label areexecuted
Braces are not necessary around multiple statements in a
case label A break statements causes execution to proceed with the
first statement after the switch
Without a break statement, execution will fall throughto the next case label
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switch statement (Cont.)
default case
Executes if no matching case label is found
Is optional
If no match and no default case
Control simply continues after the switch
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Char grade;
Cin>>grade;
switch (grade)
{
case A:
cout
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* * * * Menu * * * *
1. add
2. mul3. div
4. sub
Choose either 1, 2, 3 or 4:
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Int ch,a=10,b=20;cin>>ch;
switch (ch)
{
case 1:
cout
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While
Do while
for
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while loop repeats until condition becomesfalse
int count =1;
int total = 0;while (count
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dowhilestatement Similar to while statement
Tests loop-continuation after performing bodyof loop Loop body always executes at least once
Code: x=10;
do
{
cout
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for repetition statement
Specifies counter-controlled repetition details in
a single line of code
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Not Valid:
X for (j = 0, j < n, j = j + 3) // semicolons needed
for (j = 0; j < n) // three parts needed
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for statement examples
Vary control variable from 1 to 100 in increments of1
for ( int i = 1; i = 1; i-- )
Vary control variable from 7 to 77 in steps of7
for( int i = 7; i = 2; i -= 2 )
Vary control variable over the sequence: 2, 5, 8, 11,14, 17, 20
for( int i = 2; i = 0; i -= 11 )
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Using a comma-separated list of
expressions
for ( int number = 2;number
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Example 3: j = 1;sum = 0;for ( ; ; ){ sum = sum + j; j++;
printf"\n"
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General form of the for statement
for ( initialization; loopContinuationCondition;increment)
statement;
Can usually be rewritten as: initialization;while ( loopContinuationCondition)
{statement;
increment;}
If the control variable is declared in the initialization
expression
It will be unknown outside the for statement
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break statement
Causes immediate exit from the loop
Used in while, for, dowhile or switchstatements
continue statement
Skips remaining statements in loop body and
start from the beginning of loop
Used in for loop, while , dowhile loops
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void main ( ){
int k;for ( k= -5; k < 25; k= k+5){
cout
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void main ( )
{
int k;
for ( k= -5; k < 25; k= k+5)
{
cout
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Void main ( ){
int k;
for ( k= -5; k < 25; k= k+5)
{
cout
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int j =50;while (j < 80)
{j += 10;if (j == 70)break;
cout
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#include
#include int main() {
int n = 0;loop:
cout
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It is used to return the value to the calling
function.
It can be used in fallowing ways
a) return(expression) return(a+b);b) A function may use one or more return
statement depending upon condition
if(a>b)
return(a);
else
return(b);