ch03 loops and decisions

8/10/2019 Ch03 Loops and Decisions

1/42

Introduction to Programming

Engr. Rashid Farid [email protected]

Chapter 03: Loops and Decisions

International Islamic University H-10, Islamabad, Pakistan

http://www.iiu.edu.pk
mailto:[email protected]:[email protected]


2/42

Relational Operators //demonstrates relational operators

#include #include using namespace std;int main(){

int n;

cout > n;cout


3/42

Number SystemsBase 16 Base 10 Base 8 Base 2

0 0 0 0000

1 1 1 0001

2 2 2 0010

3 3 3 0011

4 4 4 0100

5 5 5 0101

6 6 6 0110

7 7 7 0111

8 8 10 1000

9 9 11 1001

A 10 12 1010B 11 13 1011

C 12 14 1100

D 13 15 1101

E 14 16 1110

F 15 17 1111


4/42

Bits and Bytes All data is represented internally by

computers as sequences of bits .Each bit can assume the value 0 or 1 .4 bits = 1 nibble8 bits = 2 nibble or 1 Byte210 bytes = 1 Kilo Byte or 1 KB220 bytes = 1 Mega Byte or 1 MB230 bytes = 1 Giga Byte or 1 GB240 bytes = 1 Tera Byte or 1 TB250 bytes = 1 Peta Byte or 1 PB260 bytes = 1 Exa Byte or 1 EB270 bytes = 1 Zetta Byte or 1 ZB280 bytes = 1 Yotta Byte or 1 YB290 bytes = 1 Bronto Byte 2100 bytes = 1 Geo Byte


5/42

Logic Gates and Bitwise Operators

Bitwise Operators in C++ areBitwise AND ( & )Bitwise OR ( | )

Bitwise Exclusive OR ( ^ )Bitwise NOT ( ~ )Left Shift ( > )

A B A OR B

A | B

A AND B

A & B

A XOR B

A ^ B

NOT A

~ A

NOT B

~ B0 0 0 0 0 1 1

0 1 1 0 1 1 0

1 0 1 0 1 0 1

1 1 1 1 0 0 0


6/42

Left Shift( > )//demonstrates left shift ()


short n;

cout > n;cout


7/42

Bitwise Operators #include

#include // for setw()#include using namespace std;int main( void ) {

short var1 = 0x0035 & 0x000F; // bitwise AND

short var2 = 0x0004 | 0x0068; // bitwise ORshort var3 = 0x0054 ^ 0x00F0; // bitwise XORshort var4 = ~ 0x0055; // bitwise NOT

cout


8/42

Bitwise Operators //swap two numbers without using extra variable


int A,B;

cout > A >> B;cout


9/42

Logical Operators: && , || , ! #include #include using namespace std;int main( void ) {

cout


10/42

Decision Making in C++ Often, people base their decisions on certain

conditions . For example, a person might go toa doctor if he feels sick. The decision ,whether to go the doctor, is based on acertain condition : feeling sick. The same istrue when using programs.

All of the previous programs had sequentialexecution: each statement in the programexecutes once, and they are executed in thesame order that they are listed.

You can design your program so that it selectswhich code to execute based on certainconditions.


11/42

Decision: Using the if statement The if statement allows conditional execution.

Its syntax isif (condition)

statement ;where condition is an integral expression andstatement is any executable statement.

The statement will be executed only if the valueof the integral expression is nonzero ( TRUE).When we want to run more than one statementsbased on some condition, the syntax looks like

this:if (condition){

many_statement_terminated_with ;}


12/42

Decision: Using the if statement// This program tests if one positive integer is not

// divisible by another:#include #include using namespace std;int main(){

int n,d;cout > n >> d;if (n%d)

cout


13/42

Decision: Using the if statement// demonstrates IF with multiline body


int x;

cout > x;if ( x > 100 ){

cout


14/42

Decision: Using the if statement// The Minimum of Three Integers#include #include using namespace std;int main(){

int n1,n2,n3,min;

cout > n1 >> n2 >> n3;min=n1; // now min


15/42

Decision: Using the ifelse statement The if..else statement causes one of two

alternative statements to execute depending uponwhether the condition is true. Its syntax is

if (condition) statement1 ;else statement2 ;where condition is an integral expression andstatement1 and statement2 are executable state-ments.

If the value of the condition is nonzero (TRUE)then statement1 will execute; otherwise (FALSE)

statement2 will execute.


16/42

Decision: Using the ifelse statement// demonstrates Ifelse #include #include using namespace std;int main(){

int x;

cout > x;if ( x % 2 )

cout


17/42

Decision: Using Nested if// Using Nested Selection Statements#include #include

using namespace std;int main(){

int x,y;cout > x ;

cout > y ;if ( x > 5 ){if ( y > 5 )

cout


18/42

Decision: Using the else if statement// demonstrates Ifelse #include #include using namespace std;int main(){

int age;

cout > age;if (age < 18)

cout


19/42

Decision: Using compound Conditions// using compound statements #include #include using namespace std;int main(){

int x,y; cout > x ;cout > y ;if (( x >= 5) &&( y >= 5))

cout 5) &&( y < 5))

cout = 5))

cout


20/42

Decision: Using compound Conditions// using compound statements #include #include using namespace std;int main(){

int n1,n2,n3;cout > n1 >> n2 >> n3;if (n1


21/42

Decision: Using compound Conditions// using compound statements

#include #include

using namespace std;

int main(){

char ans;cout > ans;

if (ans == 'Y' || ans == 'y' )

cout


22/42

Decision: Using the else if statement// This program converts a Marks into Grades#include

#include using namespace std;int main(){ int score;

cout > score;if (score>100) cout= 80) cout = 75) cout = 70) cout = 65) cout = 60) cout = 55) cout = 50) cout = 0) cout


23/42

Decision: Using the switch statement// demonstrates switch ... Case #include

#include using namespace std;int main(){

int x,y; char op;cout > x >> y;

cout > op;switch (op){

case '+': cout


24/42

Decision: Using the ? : statement// demonstrates ? :#include #include

using namespace std;int main(){

int m,n;cout > m >> n;

cout


25/42

Loops Loops cause a section of your program to be

repeated a certain number of times.The repetition continues while a condition istrue.

When the condition becomes false, the loopends and control passes to the statementsfollowing the loop.

There are three kinds of loops in C++:

the for loop,the while loop,

and the do...while loop.


26/42

while loop// Using Compound Statements#include #include using namespace std;int main(){

int x,loop_count=0;

cout > x ;while (loop_count


27/42

while loop// computes the sum 1 + 2 + 3 + + n,#include #include using namespace std;int main(){

int last_no, sum = 0, current_no = 1;cout > last_no;cout


28/42

Using break to terminate a loop#include #include using namespace std;int main(){

int last_no,sum=0, current_no=1;cout > last_no;

cout last_no)break ; // terminates the loop immediately

sum = sum + current_no;

cout


29/42

Using break to terminate a loop// prints all the Fibonacci numbers up to an input limit:#include #include using namespace std;int main(){

long bound;cout > bound;

cout


30/42

Using dowhile loop#include #include using namespace std;int main(){

unsigned char choice=0;do

{cout>choice;

}while (choice!='y' && (choice!='Y'));

cout


31/42

Using dowhile loop#include #include using namespace std;int main(){

long dividend, divisor;char ch;do // start of do loop

{ // do some processingcout > dividend;cout > divisor;cout


32/42

Using for loop#include #include using namespace std;int main(){

int n;

cout > n; long sum = 0;for ( int i=1; i


33/42

Using for loop#include #include #include using namespace std;int main(){

int n, i=1;cout > n;for ( ; i


34/42

Using for loop// Calculating factorial#include #include using namespace std;int main(){

unsigned long n, i, fact=1;cout > n;if ( n < 1 )

exit(0);for ( i=1 ; i


35/42

Using for loop to calculate prime#include #include using namespace std;int main(){

long n; cout > n;if (n < 2) cout


36/42

Finding Reverse using while loop// Writing in Reverse#include #include using namespace std;int main(){

long m, d , n = 0;cout > m;while ( m > 0 ){

d = m % 10; // d will be the right-most digit of mm /= 10; // then remove that digit from m

n = 10*n + d; // and append that digit to n}cout


37/42

Using continue and break// Using Writing in Reverse#include #include using namespace std;int main(){

int n;for (;;){

cout > n;if (n%2 == 0)

continue ; // Stay in Loopif (n%3 == 0)

break ; // Come out of loopcout


38/42

Assignment #21. Write a program that prints the minimum

of four input integers .2. Write a program that finds the median of

three input integers .3. Write a program to find the min of 3

numbers using ? : operator4. Using a while loop write a program to

Compute a Sum of Reciprocals of first nnumbers This program computes the sum ofreciprocals s = 1 + 1/2 + 1/3 + 1/3 + + 1/n,

5. Using nested for loops write a programto show all prime numbers in range given

by user.6. Write a program using do..while loop to

compute the sum of the first n squares , where n is input.


39/42

Assignment #21. Write a program to print out all

Armstrong numbers between 1 and 500. Ifsum of cubes of each digit of the numberis equal to the number itself, then thenumber is called an Armstrong number.For example:153 = (1*1*1) + (5*5*5) + (3*3*3)

Write a program to produce the following output usingloops:

1 2 3 4 5 6 7 6 5 4 3 2 11 2 3 4 5 6 6 5 4 3 2 1

1 2 3 4 5 5 4 3 2 11 2 3 4 4 3 2 11 2 3 3 2 11 2 2 11 1


40/42

Assignment #21. Write a program to produce the following

output using for loop:- A

A B A B C

A B C D

A B C D E A B C D E F A B C D E F

A B C D E A B C D

A B C A B

A


41/42

Assignment #2Write a program to produce the following output using

loop:- A A B

A C A D

A E A F A F

A E

A D A C

A B A


42/42

Assignment #2 ** * *

* * * * *

* * * * * * ** * * * * * * * *

* * * * * * * * * * ** * * * * * * * * * * * *

* * * * * * * * * * * * * * ** * * * * * * * * * * * * * * * ** * * * * * * * * * * * * * * * *

* * * * * * * * * * * * * * ** * * * * * * * * * * * *

* * * * * * * * * * ** * * * * * * * *

* * * * * * ** * * * *

* * **

Write a program to produce

the following outputusing loop:-

ch03 loops and decisions

Documents