Revision - Class 6

BASIC

Constant :

Value which does not change.

There are two types :

1.     Numeric Constant

2.     String Constant

Numeric constant

Numbers negative, positive, decimal or whole numbers.

Example :

 -5

1345

78.12

String Constant

This is also called Alphanumeric constant. It consists of numbers or alphabets or special characters ,it is written within double quotes(“  “).

Example :

“Cottons”

“Bangalore”

“Exam March 2014”

Variable

1.     Numeric Variable

2.     String Variable

Numeric Variable:

A variable that holds the numeric constant.

Example :

A

X1

XY

String variable

The variable that holds the alphanumeric constant. This cannot be used for arithmetic calculations. This variable must end with a $ sign.

String Variable	String Constant
Must end with $	Must be enclosed within “ “
Eg: a$,  name$,  xy$	Eg: a, xy

Operators

·        Arithmetic Operators

·        Relational Operators

·        Logical Operators

Arithmetic Operators : We are going to use all the following operators in our program, for example multiplication is  *(asterisk) not x as we use in Maths.

Addition     +

Subtraction -

Multiplication *

Division      /

Exponential  ^

Relational Operators: They are used to perform comparisons.The relational operators will give TRUE or FALSE after comparision.

Less than              <

Greater than                   >

Less than or equal to     <=

Greater than or equal to >=

Equal to                         =

Not equal to                            < >

Logical Operators: They are also called Boolean Operators.

·        AND          

·        OR

·        NOT

Let us see how the logical operator works.

Imagine a condition for getting a scholarship, either you should score above 90 in Computer science or above 80 in Maths. Assume that you have scored 85 in Computers but 87 in Maths. It is very clear that you will get the scholarship.

Computer Science (C)	Maths (M)	Result (C>90) OR (M >80)
95	63	True
71	81	True
95	100	True
46	52	False

 

The second condition is you should score above 90 in Computer science and above 80 in Maths.

Computer Science (C)	Maths (M)	Result (C>90) AND (M >80)
95	63	False
71	81	False
95	100	True
46	52	False

 

 

Commands

1. Print Command:

It is used to display the output on the screen.

Example:

Print “Hi I am in Class 6”

Print 20 *5

The  first command is within the quotes since it is a string constant. The second command calculates the expression and gives the answer 100

Print with comma

Print with semicolon

Print with Colon

Empty Print - This gives an empty line.

 

INPUT

It accepts the values from the user through the keyboard.

Difference between LET and INPUT is :

If we are using LET command the values of the program remains the same, therefore whenever we execute(RUN) the program, the output remains the same.

If we are using INPUT command, different values can be given each time we execute the program.

To accept a number:

Input A

To accept a string:

Input A$

 

 

1. Write a program to enter the side and calculate the area of a square.

        (Area of square= side x side)

Print “Enter the side”

Input S

Let area= S * S

Print area

End

 

 

Note :

Print "Enter the side" and Input S can be combined into a single statement.

Input "Enter the side" ; S

 

2. Write a program to find the area of a rectangle.

      ( Area of rectangle= Length X Breadth)

 Print “Enter Length and breadth”

Input L, B

Let A=L * B

Print A

End

3. Write a program to enter 2 numbers and display the sum, difference, multiplication and division

Print “Enter 2 Numbers”

Input a,b

Let s=a+b

Let diff=a – b

Let M=a*b

Let D=a/b

Print “Sum=” ;s

Print “Difference=”;diff

Print “Product=”; M

Print “Division=”; D

end

 

Conditional statements

This will execute the statements based on a given condition. Computer cannot take any decision , so we should instruct the computer to take some action based on the condition given by the user.

·        If Then

·        If then else

IF THEN ELSE

Syntax:

If condition then

Statement 1

Else

Statement 2

End if

 Note:
If you are using If then syntax, it will take action for only one condition , but If then Else will give you an answer for both the true condition or false condition.

1.     Write a program to enter a number check whether it is positive or negative.

(A number is said to be positive if it is greater than 0 otherwise it is negative)

Print “Enter a number”

Input N

If N > 0 then

    Print “Positive”

Else

    Print “Negative”

End if

End

 

2.     Input two numbers and display the biggest number.

Print “Enter two numbers”

Input a, b

If a>b then

    Print a “is big”

Else

    Print  b “is big”

End if
 

            End
3. If the mark entered is below 45, then you should print Fail otherwise print Pass.

         Input "Enter your mark " ; M
  
         If M > = 45 then
 
            Print "Pass "
        
         Else
      
           Print "Fail"

         End if

        End