prefix-postfix-1220980481065867-9

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3/15/2012 2

Increment operator (++)

Increases the value stored in a

variable by 1 a++ a+=1 a=a+1

are all equivalent in functionality.

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3/15/2012 3

Increment operator (++) can beused in PREFIX and POSTFIX

form.

int B=3;

int A=++B;

//output B=4

// A=4

int B=3;

int A=B++;

//output B=4

// A=3

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3/15/2012 4

Decrement operator (--)

Decreases the value stored in avariable by 1

a-- a - =1 a=a-1

are all equivalent in functionality.

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Decrement operator (--) can beused in PREFIX and POSTFIX

form.

int B=3;

int A=--B;

//output B=2

// A=2

int B=3;

int A=B- -;

//output B=2

// A=3

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Priority of Operators and

AssociativityPriority Operator Description associativity

1 :: Scope Left

2 ()[]->sizeof Left

3 ++ -- ! & *

(type) + -

Right

4 * / % Arithmetic Op. Left

5 + - Arithmetic Op. Left

6 < <= >= > Relational Op. Left

7 == != Relational Op. Left

8 && || Logical Op. Left

9 ?: Conditional Right

10 = += -= *= /= %= Assignment Right

11 , Comma Left

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Associativity

In case there are several operatorsof same priority, which one must beevaluated before-

Leftmost Rightmost

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Evaluation of expressions involving

++ and -- operators in postfix and

prefix form

PROBLEM AREA

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Examples

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#include <iostream.h>

#include <conio.h>

void main()

{ clrscr();cout <<"\n************* EVALUATION OF EXPRESSIONS*************** \n\n";

int a=10,b=20,c=30;

cout<<"a="<<a<<" b="<<b<<" c="<<c;

int z=(a++)*c/a+b;

cout <<"\nz=(a++ )*c/a+b = ";getch();

cout<<z;

}

Example 1

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Example 2


#include <conio.h>

void main()

{clrscr();

cout <<"\n** EVALUATION OF EXPRESSIONS ***\n\n";

int a=10,b=20,c=30;

cout<<"a="<<a<<" b="<<b<<" c="<<c;

z=++a*c/a+b;

cout <<"\nz=++a*c/a+b = "<<;getch();

cout<<z;

}

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#include <conio.h>void main()

{clrscr();

cout <<"\n************* EVALUATION OF EXPRESSIONS****************\n\n";

int a=1,b=2,c=3;

cout<<"a="<<a<<" b="<<b<<" c="<<c;

z= b+ c^a * ++b ;

cout <<"\nz=b+c^a * ++b; = ";

cout <<"\nAnswer is :(3+3)^(1*3) \n";

cout <<"\n :(6)^(3) \n";

cout <<"\nIn Binary :(110) XOR (011) \n";cout <<"\n :(101) \n";

cout <<"\nIn Decimal Answer is : \n";

getch();

cout<<z;

}

Example 3

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#include <conio.h>

void main()

{clrscr();

cout <<"\n* EVALUATION OF EXPRESSIONS *\n\n";z=45;

int q=45;

cout<<"\nq="<<q;

cout<<"\n-q--="<<-q--;

cout<<"q= " <<q;getch();

}

Example 4

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1. What is the screen output?

int a, b;

a = 6;

b = a++ -1;cout<<"a = " << a <<endl;

cout<<"b = " << b <<endl;


int a, b;

a = 6;

b = ++a -1;cout<<"a = " << a << endl;

cout<<"b = " << b << endl;


int i, j, k, ans;

i = 1;

j = 2;k = 3;

ans = i++ * j - --k;

cout<<ans;


int i, j, k, ans;

i = 1;

j = 2;k = 3;

ans = ++i * j - k--;

cout<<ans;


int i, j, k, m, ans;

i = 0; j = -1;

k = 0;

m = 1;;

ans = i++ && ++j || k || m++;

cout<<ans;


int a=20;

a += a++ + ++a ;cout << a;

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Evaluate the following c++ expressions where a,

b, c are integers and d and f are floating point

numbers. The values are a = 5, b=3 and d=1.5

a) f=a+b/a;

b) c=d*a+b;

c) c=a++ * d +a;

d) f=++b * b ± a;

e) c=a-(b++) * (--d);

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