1 variables - mathematics

8/13/2019 1 Variables - Mathematics

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VARIABLES, DATA TYPESAND OPERATORS


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Sample Problem

Create a program that accepts two numbers

and then display the sum. Design your own

interface. Use sampleVaras the project

name.


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Basic Data Types

Integer

Negative to positive whole number

-32,768 to 32,767 4 bytes

Float / Double Float

Real numeric value

-1038to 1038 / -1076to 1076

4 bytes/ 8 bytes

Boolean

Holds value for true or false

George Bool

Character (char) Single charactera letter, digit or a punctuation character

256 different characters

1 byteString

Combination of characters, can be digits, letters or special symbols


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Data Types

char

- the character data type.

- The char data type is used torepresent/store/manipulate character datavalues.

- A char data type value requires one byte ofmemory space.

- The range of values that can be assumed by a

char value is from 0 to 255.- The number-to-character coding that is used is

ASCII.


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Data Types

integer

- the integer data type.

- The int data type is used to

represent/store/manipulate signed whole

numeric values.


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Data Types

float

- the single precision floating point data type.

- The float data type is used to store single

precision signed real numbers (i.e., those

numbers with fractional components).


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Data Types

double

- the double precision floating point data type.

- The double data type is used to store double

precision signed real numbers.


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Notes on Data Types

Mark G. De Vera

- The amount of memory space required to store

an int, a float and double is platform-

dependent. (depends on the machine and the

software).- Note that a char data is actually numeric (from 0

to 255), and is treated as a subset of int values.

Any operation on integer values can also be

performed on characters.


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Variable Declaration

Mark G. De Vera

A variable declaration is an actionby which

a variable is introducedto a

program/function.

All variables in a program must be declared. Ifyou forgot to do so, the compiler will report a

syntax error.


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Variable Declaration

Purpose

to associate type

for storage


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Rules in Naming Variables

Mark G. De Vera

Should always start with a letter

Should be descriptive in nature

Should not be a reserved word in VB

Should not contain spaces and especial

characters except underscore (_)

Can be a combination of letters, digits and

underscore


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Declaring A Variable

Syntax:

Dim as

Dim as =

Examples

Dim lastname as String

Dim num as IntegerDim price, total_amt as Double

Dim x as Integer = 5


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Can I use any name for the var iables?

Mark G. De Vera

- YES, as long as you follow the naming

conventions, and do not use the reserved

words in VB.

- It is recommended, however, as a goodprogramming practice for you to use a name

that is descriptive or suggestive.


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What are operators?

Mark G. De Vera

Operators are symbols representingoperations that can be performed on constantsand variables.

Different sets of OPERATORS:Assignment

Arithmetic

Logical

Relational


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Assignment Operators

Mark G. De Vera

How do you per form an assignment operat ion in

VB?

Symbol used is an equal sign (=)

It is used to assign/store values to a variable.

Dim a as Integer

a=25; /*25 is assigned to a*/choice=a; /*a is assigned to choice*/


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Arithmetic Operations

Mark G. De Vera

Basic Ar i thmet ic Operat ions

+ Addition Yields the sum

- Subtraction Yields the difference

* Multiplication Yields the product

/ Division Yields the quotient

mod Modulus Division Yields the remainder


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Relational Operations

Mark G. De Vera

== Equal to

!= Not equal

> Greater than

< Less than

>= Greater than or equal


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Logical Operations

Mark G. De Vera

! Logical NOT

&& Logical AND

|| Logical OR

!0 1

!1 0

0&&0 0

0&&1 01&&0 0

1&&1 1

0||0 0

0||1 11||0 1

1||1 1


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Control Structures

Mark G. De Vera

specify the sequence of execution of a group

of statements.

Three different type of control structures

Sequential

Conditional

Loop


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Sequential Control Structure

Mark G. De Vera

A sequential control structure is organized such

that statements are executed in sequence, i.e.,

one after the other in the order of their

appearance in the source code.Example:

a = 1; /* first statement */

b = 2; /* second statement */c = a + b; /* third statement */


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Conditional Control Structure

Mark G. De Vera

The conditional control structure allows the

program to make choices depending on a

condition.

Two types of conditional structures if statement (including if-else and nested if)

switch case statement


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If Statement

Mark G. De Vera

if ()

The value of is first evaluated, if it

is non-zero, then the condition is specified as

true. If it is evaluated as zero, then the condition

is specified as false. If the condition is true, thenthe is executed.


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If Statement Example

Mark G. De Vera

void main(void)

{

int n;

printf(Input an integer value n: );

scanf(%d, &n);

if (n >= 0)

printf(n = %d is POSITIVE\n, n);

}


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If - Else Statement

Mark G. De Vera

if ()

[else ]

The value of is first evaluated, if it is non-zero, then the condition is specified as 1 (for true)and is executed. Otherwise if it isevaluated as zero, then the condition is specified as 0

(for false), and the else part, i.e., isexecuted.


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If-Else Example

Mark G. De Vera

#include

void main(void)

{

int n;

printf(Input an integer value n: );

scanf(%d, &n);

if (n >= 0)

printf(n = %d is POSITIVE\n, n);else

printf(n = %d is NEGATIVE\n, n);

}


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Nested If Example

Mark G. De Vera

if (day >= 1 && day = 600 && start_time


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Switch-Case Statement

Mark G. De Vera

#include

using namespace std;

int main(void)

{

int day;

coutday;switch(day)

{

case 1 : cout


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Loop Control Structure

Mark G. De Vera

Output

1

23

4

5

#include

void main(void)

{

printf(%d/n, 1);

printf(%d/n, 2);

printf(%d/n, 3);

printf(%d/n, 4);

printf(%d/n, 5);

}


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Mark G. De Vera

Is the previously presented source code

acceptable for you in printing the output?


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Mark G. De Vera

Three Loop Control Structures

While loop

For loop

Do while loop


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While Loop

Mark G. De Vera

while ()

#include

void main(void)

{

int i;

i = 1; /* initialization */

while (i


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For Loop

Mark G. De Vera

for ([initialization]; [condition]; [change of state])

#include void main(void)

{

int i;

for (i = 1; i


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Do While Loop

Mark G. De Vera

do

while ()

#include void main(void)

{

int i;

i = 0; /* initialization */

do /* body of the loop */

{

printf(%d\n, i);

i++; /* change of state */

} while (i


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Functions

Mark G. De Vera

a program by itselfit may have input(s),

output(s) and will perform some kind of

processing steps.

Two types of function

Pre-defined

User-defined


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Pre-defined Functions

Mark G. De Vera

those functions that have been written by for

us (by some other programmers);

Example

printf(), scanf(), exit(), strcmp()

library functions


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User-defined Functions

Mark G. De Vera

those function that we are going to

write/implement by ourselves;

Example

implementation of the main() function


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Defining a Function in C

Mark G. De Vera

()

{

[]

[]

[]

}


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Defining a Function in C

Mark G. De Vera

Example:

#include

void main(void){

int x;

x = 1;

printf(%d\n, n);}

void is the of the value

returned by the functionvoid

denotes that fact that the function

does not return anything

main is the

void is the void

denotes the fact that it does not have

any parameter

int x is the and x = 1;

printf(%d\n, n); are the

[]


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Example w/ two functions

Mark G. De Vera

#include

void hello(void)

{

printf(Hello\n);}

void main(void)

{

hello(); /* call (invoke) the function*/

}


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Examples

Mark G. De Vera

void main(void)

{

int i;

for (i = 0; i < 500; i++)

hello();

/* call inside the body of the loop*/

}


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Function with Data Type#include

int Sum(int x, int y)

{

int z;

z = x + y;

return z; /*dont forget to return a value*/

}void main(void)

{

int a, b, c;

printf(Sum = %d\n, Sum(5, 10)); /* use constants*/

c = Sum(100, 300);/*store the return value into a variable*/

printf(c = %d\n, c);

a = 25;

b = 75;

printf(Sum = %d\n, Sum(a, b)); /* use variables*/

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