PROGRAMS IN ‘BASIC’

8/8/2019 PROGRAMS IN BASIC

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PROGRAMS IN BASIC

Presentation By Jayakanth C V

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Set of directions, which is used to providean answer to some problem.

Consists of a set of instructions to be performed orcarried out in a certain order.It starts with the given data and parameters, andends up with a set of answers.

PROGRAM


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BASIC stands for Beginner's All-purpose Symbolic Instruction Code .

D esigned in 1964 by J ohn George Kemeny andThomas Eugene Kurtz at D artmouth College,USA.

BASIC


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Be easy for beginners to use.Be a general-purpose programming language.

Allow advanced features to be added for experts(while keeping the language simple for beginners).Be interactive.Provide clear and friendly error messages.

Respond quickly for small programs.Not to require an understanding of computerhardware.

The seven design principles of

BASIC


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LET - ConditionREAD - read dataDATA - Values to variablesPRINT - print a valueGOTO - go to line number IF-THEN if x , then yFOR

- for i= x to yNEXT - next value

Summary of the 15 BASIC Statements

END - end programSTOP - stop programDEF - defineGOSUB - gosub line

numberRETURN - return to xDIM - dimensionREM - remove string that is

over


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10 INPUT "What is your name: ", U$20 PRINT "Hello "; U$30 INPUT "How many stars do you want: ", N40 S$ = ""50 FOR I = 1 TO N60 S$ = S$ + "*"70 NEXT I80 PRINT S$90 INPUT " D o you want more stars? ", A$100 IF LEN(A$) = 0 THEN GOTO 90110 A$ = LEFT$(A$, 1)120 IF A$ = "Y" OR A$ = "y" THEN GOTO 30130 PRINT "Goodbye "; U$140 EN D

Example for Unstructured BASIC


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Second generation BASICs (forexample QuickBASIC and PowerBASIC)

introduced a number of features into thelanguage

Line numbering is omitted from thelanguage and replaced

with labels (for GOTO) and procedures toencourage easier and more flexible design.

Structured BASIC


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INPUT "What is your name: ", UserName$PRINT "Hello "; UserName$D O

INPUT "How many stars do you want: ", NumStarsStars$ = STRING$(NumStars, "*")PRINT Stars$D OINPUT " D o you want more stars? ", Answer$LOOP UNTIL Answer$ ""

Answer$ = LEFT$(Answer$, 1)LOOP WHILE UCASE$(Answer$) = "Y"PRINT "Goodbye "; UserName$

Example for Structured BASIC


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5 REMARK: PROGRAM TO FIN D AVERAGE HEIGHT10 LET S=020 LET N=0

30 REA D H35 REMARK: H IS THE HEIGHT OF STU D ENT40 REMARK: N IS THE NUMBER OF STU D ENTS45 REMARK: S IS THE SUM OF HEIGHTS50 LET S=S+H60 LET N=N+170 IF H=0 THEN 9080 GO TO 3090 LET A=S/(N-1)100 PRINT AVERAGE HEIGHT, A 110 D ATA 20,30,45,50,55,60,0

120 END

Program to find the Average height

of Students:


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1. All lines in the program start with a linenumber.

It is to identify the lines in the program, each one of which is called a statementIt specifies the order in which the statements are to be performed by the computer

2. Each statement starts, after its line number, with an English word.

This word denotes the type of the statement.

There are fifteen types of statements in BASIC.

OBSERVATIONS


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3. We use only capital letters.

4. Spaces have no significance in BASICIt is to pretty up a program and make it more

readable.

OBSERVATIONS cntd


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A 1X

1+A

2X

2=B

1 A 3X1+A 4X2=B 2Since there are only two equations, we may find the

solution by the formulas

Solving two Simultaneous linear

Equations


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10 REA D A1, A2, A3,A415 LET D = A1*A4-A3*A220 IF D =0 THEN 65

30 REA D B1, B237 LET X1= (B1*A4-B2*A2)/ D42 LET X2= (A1*B2-A3*B1)/ D55 PRINT X1=; X156 PRINT X2=; X260 GO TO 9065 PRINT NO UNIQUE SOLUTION70 D ATA 1, 2, 4,280 D ATA -7, 5

90 EN D

BASIC Program for Solving two

Simultaneous linear Equations


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First statement, numbered 10, is a REA D statement.

The variables whose names are listed after theREA D will be given values according to the nextavailable numbers in the D ATA statements.The statement, numbered 15, is LET statement.It compute the value of the expression A 1 A 4-A 3 A 2,and assigns this value to the variable D .

Interpretation


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In line 20 the computer asks a question: Is D equalto 0.If the answer is yes, then the next statement to beexecuted by the computer is the one numbered 65.If the answer is no, the computer continues tostatement 30.

Interpretation cntd


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In line 30, the computer causes the variable B1 andB2 to be given the value next appearing in theD ATA statement .The statements numbered 37 and 42 complete thecomputation of the solution, X1 and X2.

Then statement 60 tells the computer to executenext statement 30 will cause the variables B1 andB2 to be given the values 1 and 3, respectively.

Interpretation cntd


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If D , the determinant of the coefficients, is zero, weknow that the set of equations does not have aunique solution.In this case, statement 20 will cause the computer toexecute statement 65 next.

Instead of numerical answers being printed out, it will produce the English message NO UNIQUESOLUTION

Interpretation cntd


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Thank you

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PROGRAMS IN ‘BASIC’