MELJUN CORTES C++_Chap2

8/10/2019 MELJUN CORTES C++_Chap2

1/55

Introducing C

s Program

Control Statements

C Programming Language

Chap. 2

MELJUN CORTES MBA MPA BSCS


2/55


School of Computer I nformation 2

Objectives

Cs most important program controlstatements if, for

Determine your programs flow of execution.

Form the backbone of your programs.

Well learn

Blocks of code

The relational and logical operatorsMore printf()


3/55



Ex. 1

Read two numbers to A and B. Increase 1 number to A and decrease 1 number to B.

START

A = A + 1

B = B - 1

END

A, B

READ A, B

#include

void main() {

int a, b;

printf(Input two numbers : );

scanf(%d%d, &a, &b);

}

a = a + 1;b = b - 1;

printf(As value : %d\n, a);

printf(Bs value : %d\n, b);


4/55



Ex. 2

Read two numbers to A and B.Swap A for B.

A B

A B

temp


5/55



1. Become familiar with the if

If statements Cs selection statements

Conditional statements

Logical data

true

false

C doesnt have boolean datatype.

Use int, char datatype for logical data

if(expression) statement ;

Execute when expression is true

The result is true or false


6/55



if (10>9) printf(true);


Relational operator > : greater than

expression

statement

true

false


7/55MELJUN CORTES MBA MPA BSCS


if (9 < 5) printf(this will not print);


Relational operator < : less than





Example 1

#include

int main(void) {

int answer;

printf(What is 10 + 14 ? );

scanf(%d, &answer);

if(answer == 10+14)printf(Right!);

return 0;

}





Example 2 (feetmeters conversion program)





Exercises

Write a program that asks the user for an integer

and then tells the user if that number is even or odd.(Hint, use Cs modulus operator %.)




Two-way Selection statement

2. Add the else




if

else logic flow

2. Add the else




Example 1

2. Add the else




Example 2

2. Add the else




Exercises

2. Add the else

Write a program that requests two numbers and then

displays either their sum or product, depending on

what the user selects.

input two number : 28 5

select operator ( 1 : sum, 2 : product ) : 1

28 + 5 = 33




Exercises

2. Add the else

Write a program that requests two numbers and then

displays bigger number.

input two number : 28 5

28 > 5


17/55



Code block : { the statements }

3. Create blocks of code

One logical

unit

One logical

unit


18/55



If the user enters any positive number, thisfragment prints the message


scanf(%d, &num) ;

if(num > 0) {

printf(This is ) ;

printf(an example of ) ;

printf(a code block.) ;

}


19/55



Example 1



20/55



Example 2



21/55



Exercises


Write a program that either adds or subtracts two

integers. First, prompt the user to choose an operation;

then prompt for the two numbers and display the result.

select operator ( 1 : add, 2 : subtract ) : 1

input two number : 28 528 + 5 = 33


22/55



Cs loop statements for loop / while loop / do.. while loop

forloop allows one or more statements to be

repeated.

General form of forloop

Initialization

Conditional-test

increment

4. Use the forloop

for (initialization; conditional test; increment)

statements;


23/55



Initialization Use to give an initial value to loop-control variable

Execute only once before the loop begins

Conditional-test

Is performed at the start of each iteration. Test the loop-control variable against a target value

True the loop repeat

False the loop stop

Increment Is executed at the bottom of the loop

Increase or decrease the loop-control value by a certain

amount

4. Use the forloop


24/55



4. Use the forloop

for statement


25/55



4. Use the forloop

Simple exampleThis program uses a for loop to print the

numbers 1 through 10 on the screen

#include

int main(void){

int num;

for(num=1; num


26/55



4. Use the forloop

Example (loop will not execute)

#include

int main(void){

int num;

//this loop will not execute

for(num=11; num


27/55



4. Use the forloop

Example (A for loop can run negatively)

#include

int main(void){

int num;

//this loop will not execute

for(num=20; num>0; num=num-1)

printf(%d , num) ;

printf(terminating);

return 0;

}20 19 18 17 3 2 1 terminating


28/55



4. Use the forloop

Using block to repeat several statements This program computes the product and sum of the

numbers from 1 to 5.

#include

int main(void){

int num, sum, prod;

sum = 0;

prod = 1;

for(num=1; num


29/55



4. Use the forloop

Example (increment or decrement by more than one) This program counts to 100 by fives.

#include

int main(void){

int i;

for(i=0; i


30/55



4. Use the forloop

Example 1. (addition-drill)


31/55



4. Use the forloop

Example 2. (determination of prime number)


32/55



4. Use the forloop

Exercises 1.

Create a program that prints the numbers from 1 to 100.

1 2 3 8 9 10: : : :: : : :: : : :

91 92 93 98 99 100


33/55



4. Use the forloop

Exercises 2.

Write a program that prints the numbers between 17 to

100 that can be evenly divided by 17.

34 51 68 85


34/55



4. Use the forloop

Exercises 3.

Write a program similar to the prime-number tester,

except that it displays all the factors of a number entered

By the user.

For example, if the user entered 8, it would respond with

2 and 4.

Enter a number : 8

8s factor => 2 4

5 Substitute Cs increment and


35/55



5. Substitute C s increment anddecrement Operators

Increment operator (++) num = num +1; num++;

Using for loop

Decrement operator (--)

count = count -1; count--;

for(num=1; num


36/55




The Position of increment/decrement operator(++, --) Although the effect on the variable is the same, the position

of the operator does affect when the operation is performed.

#include

int main(void){

int i, j;

i = 10;

j = i++;

// this will print 11 10

printf(i and j : %d %d\n, i, j) ;

return 0;

}



37/55




After the variable ( num++ )

If max = 1

Result

max = 2, count = 10

First : the current value of variable is used for expression.

After : increment expression execute.

Arrangement

count = 10 * max++;

count = 10 * max++;count = 10 * max;

max = max + 1;



38/55




Before the variable( ++num )

First : increment expression execute.

After : the incremented value of variable is used for

expression.

#includeint main(void){

int i, j;

i = 10;

j = ++i;

// this will print 11 11

printf(i and j : %d %d\n, i, j) ;

return 0;

}


39/55



40/55




Example 1.

5. Substitute Cs increment and


41/55




Example 2.



42/55




Exercises 1.

Change all appropriate assignment statements in this program

to increment or decrement statements.

#include

int main(void) {int a, b;

a=1;

a = a + 1;

b = a;

b = b 1;

printf(%d %d, a, b);

return 0;

}



43/55




Exercises 2.

Enter a number. Compute summation until the number

from 1.

enter a number : 10

sum of 1 ~ 10 : 55



44/55




Exercises 3.

Enter a number. Compute factorial of the number.

enter a number : 33! = 6

enter a number : 5

5! = 120

enter a number : 10

10! = 3628800

6 Expand printf()s capabilities


45/55



6. Expand printf() s capabilities

Backslash codes

Represent characters that cannot be entered from the keyboard,

and non-printing characters

Escape character



46/55




'\n' (newline character)

It translates it into a carriage return/linefeed combination.

backslash codes are character constants.

char ch;

ch = '\t'; /* assign ch the tab character */



47/55



number square cube

===============================1 1 1

2 4 8

3 9 27

: : :10 100 1000


ExerciseUsing forloop (1~10)

7. Program with Cs relational


48/55



gand Logical operators

Relational operators Compare two values and return a true or false result based

upon that comparison.

Logical operators

Connect together true/false results.



49/55




Truth table (AND, OR, NOT)



50/55




Precedence of operators The relational and logical operators are both lower in

precedence than the arithmetic operators.

10 + count > a + 12 (10 + count) > (a + 12)

var > max || ! (max==100) && 0


51/55




Example 1.

if(count != 0) if(count)

The expression !count is true only if count is zero.

if(count == 0) if(!count)



52/55




Example 2. (the outcome of a relational or logical operation)



53/55




Example 3. (exclusive-OR)

XOR truth Table

A function of XOR



54/55



and Logical operators

Example 3. (exclusive-OR) Demonstrate the xor()

Skills Check


55/55

Skills Check

Page 66 ~ 67

Documents

MELJUN CORTES C++_Chap2