Flipp Book Class-8 new1

Syntax : EXIT {DO | FOR } Examples: EXIT FOR EXIT DO Sample Programs of loop. A nested loop contains at least one loop. Nested loop should not cross a. CLS with each other and each loop of nested FOR I = 1 TO 10 must have unique variable name. PRINT I IF I = 5 THEN EXIT FOR Format of nested Loop NEXT I END FOR I • Here, when the value of I=5 then ex- [Statement block ecution control flow comes out of loop. It does not repeat the normal loop as …………………. given 10 times. …………………] b. CLS PRINT \"Enter negative to exit from FOR J the loop\" I=1 [Statement block DO WHILE I <= 10 INPUT \"Enter positive Num- …………………. ber:\"; N S=S+N …………………] IF N < 0 THEN EXIT DO LOOP NEXT J PRINT \"Sum=\"; S END [Statement block • Here, if you type negative number, the …………………. execution flow comes from the out of loop. It does not allow to repeat state- …………………] ment block which mentioned within DO WHILE – LOOP. NEXT I Nested Loop Sample Programs A loop comes inside a loop is called a. CLS nested loop. In the programming, some time it is necessary to use such type FOR I = 1 TO 5 FOR J = 1 TO I PRINT J; NEXT J PRINT NEXT I END Smart Computer Science Book-8 395

Output ................................................... NEXT J PRINT ................................................................ NEXT I END ................................................................ Output ................................................... ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ .......................................................... ................................................................ b. CLS FOR I = 5 TO 1 STEP-1 FOR J = 1 TO I PRINT “*”; Points to Know • Looping is programming technique which helps to repeat a task again and again for specified number of times or as long as specified condition is matched. • The statements which are used to repeat a task for number of times are called loop statements. • QBASIC supports three types of versatile loop statements : FOR-NEXT, WHILE- WEND and DO-LOOP. • Pre-Test: structure controls the loop in the entry point. • Post Test: This structure controls the loop in the exit point. Terms to Know Looping : A process in which a list of statements executes repeatedly. Loop : Repeating a task for specified times. Flow : The order in which instructions of program are executed Entry Point : Start instructions of a program are executed. Exit Point : End instructions of a program are executed. Execution : Running the program and getting action. Condition : Situation of a case. Pretest : Test the condition in the entry point in program. Post test : Test the condition in the exit point. 396 Looping Statements

Worksheet Objective Questions 1 . Fill in the Blanks: a. ...................... variable is an optional with NEXT. b. The statement which is used to repeat a task is called...................... statement. c. STEP is an ................... clause. d. Never ending loop is called...................loop. e. A loop lies inside a loop is called .................. loop. f. The pre-test loop structure controls the loop in the ........................ point. g. The post test loop structure controls the loop in the ........................ point. 2 . Match the following: Repetition of task a. FOR LOOP b. WHILE NEXT c. DO WEND d. LOOPING 3. State whether the following statements are true or false: a. String expression can not be used with test condition of WHILE-WEND. b. The body of loop must change the value of the variable used in the test condition. c. Variable used in test condition can be initialized in any places of program. d. Loop can be repeated forward and backward. e. Fraction value can not be used as a increment or decrement values in loop. f. There is not any difference between pre-test and post test in the result. g. It is not possible to exit from WHILE-WEND with EXIT statement. Smart Computer Science Book-8 397

Descriptive Questions 1. Answer the following questions: a. What is looping? b. What do you mean by loop statement? c. Differentiate between pre-test and post-test condition. d. What is nested loop? e. Differentiate between WHILE and UNTIL condition. f. Differentiate between semicolon and comma with the end of PRINT statement. g. When does FOR-NEXT loop not come in action? h. What do you mean by infinite LOOP? i. When does infinite loop exist? j. How do you break down the infinite loop? Analytical Questions Output .................................................. 1. Write the output of following ............................................................... programs: ............................................................... a. CLS FOR I = 1 TO 9 STEP 2 ............................................................... PRINT I; NEXT I ............................................................... END ............................................................... Output ................................................... b. CLS ............................................................... c. CLS I=1 DO UNTIL I>5 N=5 PRINT I, I^3; F=1 I=I+1 I=1 LOOP DO END F=F*I I=I+1 LOOP UNTIL I > N PRINT F END Output .................................................. 398 Looping Statements

d. CLS ................................................................ A = -25 FOR I = 1 TO 10 ................................................................ PRINT A; A=A+5 ........................................................... NEXT I 2. Debug the following programs: END a. CLS Output .................................................... REM : To find the sum of 1 to 10 FOR I= 1 TO 10 e. CLS S=S+1 FOR I = 5 TO 1 STEP-1 NEXT S PRINT \"Sum=\";S FOR J = 1 TO I END PRINT \"*\"; Ans ........................................................ NEXT J ................................................................ PRINT ................................................................ NEXT I ................................................................ END Output ................................................... ................................................................ ................................................................ ................................................................ ................................................................ .......................................................... b. CLS ................................................................ REM: Print your name 10 times. ............................................................ IMPUT \"Enter your Name:\";N I=1 f. CLS WHILE I<10 FOR I = 5 TO 1 STEP-1 PRINT N$ I=I+1 FOR J = I TO 1 STEP-1 LOOP END PRINT j; Ans: ....................................................... NEXT J PRINT NEXT I END Output ................................................... ................................................................ ................................................................ ................................................................ Smart Computer Science Book-8 399

................................................................ h. Write a program to ask 10 numbers and find their sum. ................................................................ i. Write a program to display: ................................................................ 5 45 ................................................................ 345 2345 ........................................................ 12345 c. CLS Project base Work REM : Display square of 10 TO 5 FOR I=10 TO 5 1. In the chart paper, write an algorithm, DISPLAY I flowchart and program codes of QBA- NEXT I SIC to ask age of 25 students and find END the number of students in the follow- ing age group. Ans: ....................................................... Age group Numbers ................................................................ <10 ? ................................................................ 10 to 15 ? ................................................................ >15 ? ............................................................... 2. In the chart paper, write an algorithm, ............................................................... flowchart and program codes of QBA- SIC to ask all the subject marks of to- ................................................................ tal number of students of your class 3. Write a program for the following and find the grade as given. tasks: Avg. Marks Grade a. To ask word \"WELCOME\" print 10 times. b. To display multiples of 5 up to 10th terms. >90 A+ c. To display only even numbers from 2 to >80 A 20. d. To display only odd numbers from 1 to 20. >70 B+ e. Write a program to display following: 50, 45, 40, 35,................5. >60 B f. Write a program to display 20, 18, 16, 14, >50 C+ 12.................2. g. Write a program to display 100, 81, >40 C 64................1. <=40 D 400 Looping Statements

Library Functions CHAPTER Juna : Wow ! I saw, Nikita was 19 using some functions in the program. How does This chapter includes: Function work, Merry ? • Introduction of Function and Types • Common Library Func- tions. Muna : Well, Function is a ready • String, Mathematical, Date made program. Once, it Time, Input/output func- tions. is created, simply we can use any where in the pro- gram as we like. Juna : Okay ! How many types of functions are there Ma'am ? Muna : Basically, there are two types, built in function and user defined function. Juna : Why is it used ? Muna : It reduces the instructions and easily we can instruct to the computer. Lt's see in detail. INTRODUCTION OF FUNCTIONS QBASIC supports predefined or readymade programs code to perform the specific task are called functions, which take data, processes them and return a value in numeric or string type. Once a function is made, it can be used again and again in any part of the program. Every function has given a unique Smart Computer Science Book-8 401

name that name is used to execute a function in a program called calling func- tion. When function is calling, it needs data or values that we should pass. The data or values passed into the function is called passing argument. Function can be called in two method one is with PRINT statement and another is as- signing the return value in a variable. For example: PRINT LEN (“Kathmandu”) • Here, LEN is a function which is calling with PRINT statement; “Kathmandu” is passed argument into this function. It displays length of passed string “Kathmandu” which is 9. S=SQR(4) • Here SQR is a function name which returns the square root of passed argument 4 and assign in the S variable. The content of S will be 2. QBASIC supports two types of functions: 1. Library functions 2. User defined functions. User Defined functions are needed to define ourselves during the program- ming when we need; then only we can use. Such functions are not available to all the programs. Library Function comes automatically with QBASIC system which can be used with any program. These are also called built-in functions. The library functions should be called by programmer to use in the program. Library func- tions also different types such as string, mathematical, date and time, I/O, etc. LEN () Function Function : It is a string processing function which returns the number of characters in a string or the number of bytes stored by a variable. Syntax : LEN (string expression) • String expression may be string constant or variable Example : CLS W$= “SAGARMATHA” PRINT LEN(W$) END • Here, it displays 10, which is number of characters or bytes stored in the W$. 402 Library Functions

LEFT$ () Function Function : Its function is to return the specified number of characters from the left most side of the string. Syntax : LEFT$(string expression, n) • Where string expression may be a string variable or string constant. N is an integer value or variable that represents numbers of characters extracted from left most side of the character. Example : CLS PRINT LEFT$(“KATHMANDU”,3) END • Here, it extracts 3 characters KAT from the left hand side of passed string “KATHMNADU”. Sample Programs Output ................................................ ............................................................. a. CLS ............................................................. W$ = \"PATAN\" .............................................................. FOR I = 1 TO 5 ............................................................. PRINT LEFT$(W$, I) NEXT I END • Here, first time it extracts one character P from left hand side of X$ because value of I =1, second time, it extracts two character PA because value of I will be 2 and so on, the loop repeats five times. b. CLS Output ................................................ W$ = \"PATAN\" ............................................................. N=5 ............................................................. FOR I = 1 TO LENT(W$) .............................................................. PRINT LEFT$(W$, N) N=N-2 ............................................................. NEXT I END • Here, it extracts five characters from left hand side of the string because value of N=5. Second time it extracts three character because value of N is decreased by 2 and so on, Smart Computer Science Book-8 403

the loop repeats five times because length of string is 5. RIGHT$ () Function : RIGHT$ is a string function which is used to extract the specified num- ber of characters beginning from the right most character of the string. Syntax : RIGHT$(string expression, n) • Where string expression may a string variable or string constant. N is an integer value or variable in the range 0 to 32767 that represents numbers of characters extracted from right most side of the character. Example : CLS PRINT RIGHT$(“KATHMANDU”,4) END • Here, it extracts 4 characters ANDU from the right hand side of passed string “KATHMNADU” Sample Programs Output ................................................ a. CLS ............................................................. ............................................................. W$ = \"PATAN\" .............................................................. FOR I = 1 TO LEN(W$) ............................................................. PRINT RIGHT$(W$, I) NEXT I END • Here, it extracts one character N from right hand side of X$ because value of I =1, second time, it extracts two character AN because value of I will be 2 and so on, the loop repeats five times because length of string is 5 which is used as final value to control the loop. b. CLS Output ................................................ W$ = \"PATAN\" ............................................................. FOR I = LEN(W$) TO 1 STEP-2 ............................................................. PRINT RIGHT$(W$, I) .............................................................. NEXT I END ............................................................. • Here, it extracts five characters PATAN from right hand side of the string because first time value of I=5 which is the length string. Second time it extracts three character TAN because value of I is decreased by 2 and so on. 404 Library Functions

MID$ () Function Function : MID$() is used to extract specified number of characters from a string. It is more powerful than LEFT$ () and RIGHT$ () because it can per- form the task which is performed by LEFT$() and RIGHT$(). Syntax : MID$(string expression, start, n) • Where string expression may be a string variable or string constant. Start rep- resents the position measured from the left-most character of passed string. n represents number of characters to extract. Example : PRINT MID$(“KATHMANDU”,1,3) ‘ it extracts KAT from the first position three characters. PRINT MID$(“KATHMANDU”,4,3) ‘ it extracts HMA from the 4th position three characters. PRINT MID$(“KATHMANDU”,7,3) ‘ it extracts NDU from the 7th position three characters. Sample Programs Output ............................................... .............................................................. a. CLS ............................................................. W$ = \"PATAN\" ............................................................. SP = 3 .............................................................. N=1 FOR I = 1 TO 3 PRINT MID$(W$, SP, N) SP = SP - 1 N=N+2 NEXT END • Where SP represents starting position and N represents number of character. b. CLS W$ = \"PATAN\" SP = 1 Output ............................................... N=5 .............................................................. FOR I = 1 TO 3 PRINT MID$(W$, SP, N) ............................................................. SP = SP + 1 ............................................................. N=N-2 .............................................................. NEXT END • Where SP represents starting position and N represents number of character. Smart Computer Science Book-8 405

Test Your Skill Ans:......................................................... ................................................................ 1. Write a program to display: ................................................................ a. P ................................................................ ................................................................ PRO ................................................................ PROGR ................................................................ PROGRAM ................................................................ ...................................................... Ans:......................................................... ................................................................ d. PROGRAM ................................................................ ROGRA ................................................................ OGR ................................................................ G ................................................................ ................................................................ Ans:........................................................ ....................................................... ................................................................ b. PROGRAM ................................................................ ................................................................ PROGR ................................................................ PRO ................................................................ P ................................................................ Ans:......................................................... ................................................................ ................................................................ e. B ................................................................ ................................................................ BO ................................................................ BOO ................................................................ BOOK ................................................................ Ans:........................................................ ....................................................... ................................................................ c. G ................................................................ ................................................................ OGR ROGRA PROGRAM 406 Library Functions

................................................................ position. ................................................................ Ans:........................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ f. PROGRAM ................................................................ ................................................................ PROGRA ................................................................ PROG 3. Write a program to ask your name and PRO PR print length. P Ans:........................................................ Ans:........................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ 2. Write a program to ask your name and print first two characters, last 2 char- acters and 3 characters from second LCASE () Function Function : It is a string function which is used to convert all uppercase characters in lowercase. Syntax : LCASE(string expression | variable) • String expression may be a string constant or string variable. It may refer to a fixed- or variable-length string. Example : CLS W$= “KATMANDU” PRINT LACASE$(W$) Output ........................................... PRINT UCASE$(\"LALITPUR\") ......................................................... END Smart Computer Science Book-8 407

• Here, it displays the content of W$ into lowercase. UCASE () Function : It is a string function which is used to convert all lowercase characters in uppercase. Syntax : LCASE (string expression) • String expression may be a string constant or string variable or string expres- sion. It may refer to a fixed- or variable-length string. Example : CLS W$= “KATMANDU” PRINT UACASE$(W$) Output ........................................... PRINT UCASE$(\"LALITPUR\") ......................................................... END • Here, it displays the content of W$ into uppercase. Test Your Skill 2. Write a program to ask your name in small letter and change into capital 1. Write a program to ask your name in letter. capital letter and print in small letter case. Ans:......................................................... Ans:........................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ TAB () Function Function : The TAB is a device I/O function that moves the print position when used with the PRINT or LPRINT statements. Syntax : TAB(column) • Where, column is a numeric value represents column number of monitor. There are 24 rows and 80 columns on the standard screen. Example : CLS PRINT TAB(1); “A” PRINT TAB(40); “B” 408 Library Functions

PRINT TAB(80); “C” END • Here, program prints A, B, C in column number 1, 40 and 80 respectively. Output: SPC () Function Function : The SPC is a device I/O function that skips n spaces in a PRINT or LPRINT statement. Syntax : SPC (n) • Where n is a numeric expression that returns an integer value between 0 and 32,767, is the number of spaces you want in print line Example : CLS X$ = \"Rahul\" Y$ = \"Kumar\" Z$ = \"Chhetri\" PRINT SPC(1); X$; SPC(5); Y$; SPC(10); Z$ END • Here, the program displays the ‘Rahul’ is column number 2 because it skips one column in the beginning. Then it displays ‘Kumar’ after skipping 5 spaces from the beginning position and it displays ‘Chhetri’ after skipping 10 spaces. Output: SQR () Function Function : The SQR is a mathematical function that returns the square root of any positive number. Syntax : SQR(n) • Where, n is a positive number or numeric expression. Example : CLS PRINT \"Value\", \"Square Root\" Smart Computer Science Book-8 409

FOR I = 1 TO 5 Output ........................................... READ N ......................................................... SR = SQR(N) ......................................................... PRINT N, SR ......................................................... NEXT I DATA 4, 9, 16, 25, 100 ......................................................... END ......................................................... SGN () Function Function : The SGN is a mathematical function that returns sign of a number, the number may negative, positive or zero. Syntax : SGN(n) • Where, n is a numeric expression. If n is positive, the SGN function returns +1. If n is zero, the SGN function returns 0. If n is negative, the SGN function returns -1. Example : CLS Output ........................................... FOR I = 1 TO 5 ......................................................... READ N ......................................................... S = SGN(N) ......................................................... PRINT N, S ......................................................... NEXT I DATA 10,-15, -20, 0, 50 ......................................................... END 410 Library Functions

Points to Know • QBASIC supports predefined or readymade programs code to perform the specific task is called functions • Once a function is made, it can be used again and again in any part of the program. • The data or values passed into the function is called passing argument. • Function can be called in two method one is with PRINT statement and another is assigning the return value in a variable. • QBASIC supports two types of functions Library functions and user defined func- tions. • User Defined functions are needed to define ourself during the program- ming. • Library Function come automatically with QBASIC system which can be used any program. Terms to Know Function : Readymade programs code which can be called as we like. Argument : Data or values passed into the function. Lowercase : Alphabets written in small letter. Uppercase : Alphabets written in capital letter. Smart Computer Science Book-8 411

Worksheet Objective Questions 1 . Fill in the Blanks: a. ...................... is used to convert lowercase character to uppercase. b. ........................... is used to extract specified number of characters from extremely left hand side of the string. c. ........................... is used to extract specified number of characters from middle of the string. d. .......................... is used to find the number which is negative, positive or zero. e. ...................... is used to find the length of the string. f. ........................... is used to extract specified number of characters from extremely right hand side of the string. g. ...................... is used to convert uppercase character to lowercase. 2. State whether the following statements are true or false: a. SPC () is a device input/output function. b. User defined function is also called built-in function. c. Variable used in test condition can be initialized in any places of program. d. Library functions are available with QBASIC. e. SQR () is a string function. f. LEN() is a mathematical function. g. TAB() is a device input/output function. 412 Library Functions

Descriptive Questions 1. Answer the following questions: a. What do you mean by function? b. What you mean by calling function? c. What do you mean by argument d. In how many way can you call function? Name them. e. What do you mean by User define function? f. What do you mean by Library Function? g. Why is MID$() is more powerful than LEFT$() and RIGHT$() ? h. How can you find a number is negative, positive or zero? Analytical Questions c. CLS W$ = \"NEPAL\" 1. Write the output of Following: N=1 a. CLS FOR I = 1 TO LEN(W$) PRINT LEFT$(W$, N) W$ = \"NEPAL\" N=N+1 FOR I = LEN(W$) TO 1 STEP -1 NEXT I X$ = X$ + MID$(W$, I, 1) END NEXT I PRINT X$ Output : ................................................ END ............................................................... Output : ................................................. b. CLS ............................................................... W$ = \"NEPAL\" ............................................................... FOR I = 1 TO LEN(W$) X$ = MID$(W$, I, 1) + X$ ............................................................... NEXT I d. CLS PRINT X$ END W$ = \"NEPAL\" N=1 Output : ................................................. Smart Computer Science Book-8 413

SP = 1 PRINT TAB(T); \"*\" FOR I = 1 TO LEN(W$) T=T-1 PRINT MID$(W$, SP, N) NEXT I SP = SP + 1 END NEXT I END Output : .................................................. Output : ................................................ .................................................................. ............................................................... .................................................................. ............................................................... .................................................................. ............................................................... .................................................... ............................................................... g. CLS e. CLS W$ = \"NEPAL\" W$ = \"NEPAL\" N=1 SP = 1 SP = 5 FOR I = 1 TO LEN(W$) N=1 PRINT MID$(W$, SP, N) SP = SP - 1 FOR I = 1 TO LEN(W$) NEXT I END X$ = MID$(W$, SP, N) Output : ................................................ R = I MOD 2 ................................................................ IF R = 0 THEN ................................................................ PRINT LCASE$(X$) ................................................................ ELSE ................................................................ PRINT UCASE$(X$) ......................................................... END IF f. CLS SP = SP + 1 T = 40 FOR I = 1 TO 5 NEXT I END Output : .................................................. .................................................................. .................................................................. .................................................................. .................................................... 414 Library Functions

2. Write a program to display the following: a. Write a program to ask a word and display first character, last characters and two characters from second position. b. Write a program to ask a word and display only alternate characters. [NEPAL as NPL) c. Write a program to as a word in small letter and print in alternate letters in capi- tal letters.[Hint: nepal as NePaL) d. Write a program to ask a your name and find out total vowel letter. e. Write a program to ask your name and find out how many times 'e' or 'E' is re- peated. f. Write a program to ask a word and display in reverse order. g. Write a program to ask a word and find out total number of characters. 3. Write a program to display following: a. M e. 1 MA 2 MAD MADA 3 MADAM 4 5 b. MADAM DAM f. MADAM M MADA MAD c. D ADA MA M MADAM g. SONAM d. M ONA A N D A h. N M ONA SONAM Smart Computer Science Book-8 415

4. Debug the following programs: c. CLS a. CLS REM :To print 3 characters from sec- ond position REM : To display a word in reverse or- W$=\"NEPAL\" der. PRINT MID$(W$, 3) W$=\"NEPAL\" END FOR I=1 TO 5 STEP-1 X$=X$+MID$(W$,I,1) Ans:........................................................ NEXT I ................................................................ END ................................................................ Ans:........................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ .......................................................... ................................................................ d. CLS ........................................................ REM : To print each character of in b. CLS right diagonal: W$=\"SHANTA\" REM : To find the length of a string FOR I=1 TO LEN$(W$) ENTER \"Enter a word:\";W$ X$=LEFT$(WI$, I, 1) L=LENGTH(W$) PRINT TAB(T); X$ PRINT L T=T-1 END NEXT I END Ans:........................................................ Ans:........................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ 416 Library Functions