HOW TO PROGRAM A CALCULATOR USING QBASIC

Using QBasic is not very common with most of the programmers. QBasic is a very good start for learner in programming. In this write up you'd see how to program a calculator that works perfectly. although it is just a simple calculator but it is a good start for start for new born programmer. I hope you find it very useful and visit this blog for more of it kind. Before you start you should have installed the QBasic software but let me recommend QBasic 64 for you commonly known as qb64. After the installation you can get started. CLS SCREEN 13 PRINT "CALCULATOR-" PRINT "ENTER YOUR EXPRESSION" PRINT "EXAMPLE-58 * 20" PRINT "THE TERMS SHOULD BE SEPARATED BY SPACE OR ERROR WILL OCCUR" INPUT "ENTER YOUR EXPRESSION-"; EXP$ EXP$ = EXP$ + " " INDEX = 1 DIM TERMS(3) AS INTEGER FOR I = 1 TO LEN(EXP$) CURRENTTOKEN$ = MID$(EXP$, I, 1) IF CURRENTTOKEN$ = " " THEN IF INDEX = 2 AND OPERATION$ = "" THEN OPERATION$ = TERMCURRENT$ ELSE TERMS(INDEX) = VAL(TERMCURRENT$) INDEX = INDEX + 1 END IF TERMCURRENT$ = "" ELSE TERMCURRENT$ = TERMCURRENT$ + CURRENTTOKEN$ END IF NEXT I SELECT CASE OPERATION$ CASE "+" R = TERMS(1) + TERMS(2) CASE "*" R = TERMS(1) * TERMS(2) CASE "-" R = TERMS(1) - TERMS(2) CASE "/" R = TERMS(1) / TERMS(2) CASE "%" R = TERMS(1) MOD TERMS(2) CASE "^" R = TERMS(1) ^ TERMS(2) END SELECT PRINT TERMS(1); OPERATION$; TERMS(2); "="; R Now you've finished coding you should now run your program. Note : to run your program, you save it with .bas extension other wise it will not work.