Learning qbasic and im trying to understand the code I just wrote

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So I had a problem on a hw assignment that told me to print a triangle out of stars.

I ended up guessing and checking and pulling out this.

VB

DIM LINES AS INTEGER
CLS

INPUT "How many lines will your triangle be: ", LINES

FOR x = 1 TO LINES
    PRINT
    FOR y = 1 TO x
        PRINT "*";
    NEXT y
NEXT x
END

The Code works but I dont understand how. I've picked up programming fast, but nested loops have left me confused most of the time. I now its weird to be learning qbasic but that is what my school offers. Can someone please explain the code I just wrote. And help me with DO, and FOR commands. Thank You I am really far ahead with the HW so my teacher isnt helping.

What I have tried:

I guess and checked the code and am now confused. An explanation is all im asking for. Tried to self explain but, didnt understand it.

Posted 26-Sep-16 15:04pm

G-MINOR

Updated 26-Sep-16 16:02pm

Blutfaust

v2

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2 solutions

Solution 2

I would recommend to use the debugger, but I don't remember if it was efficient in QBasic.
Try this link from Standord University:
Learn to Program[^]
and this one
https://www.khanacademy.org/computing/computer-programming/programming/looping/p/nested-for-loops[^]

Search for tutorials as you need.

Posted 26-Sep-16 16:02pm

Patrice T

Updated 7-Oct-16 14:24pm

v3

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Garth J Lancaster · Accepted Answer · 2016-09-26T15:29:00

I would have started on a piece of paper, since you only have 3 variables, LINES, X, Y

I'm going to use a notation a <- b means that a becomes the value of b

LINES <- 5 as a start point

X <- 1 (out of 5)
Y <- 1 (out of X which equals 1)
Print "*"
Line 1, one "*" printed

X <- 2 (out of 5)
Y <- 1 (out of X which equals 2)
Print "*"
Y <- 2 (out of X which equals 2)
Print "*"
Line 2, two "*" printed

X <- 3 (out of 5)
Y <- 1 (out of X which equals 3)
Print "*"
Y <- 2 (out of X which equals 3)
Print "*"
Y <- 3 (out of X which equals 3)
Line 3, 3 "*" printed

So for every line 'X' in my case 5 (Lines), Im going to use 'Y' to print the number of stars on that line - which equals X stars - 1st line has 1 star, 2nd has 2 stars, 3rd line has 3 stars, 4th line has 4 stars, 5th line has 5 stars

btw, in between the two loops X Y ie

VB

NEXT Y
NEXT X

I would have done something like

VB

NEXT Y
PRINT (something to make a new line)
NEXT X

but its been a long time since Ive done any BASIC so you'll have to look that up

does that help ?

[EDIT]

Its also easier to see 'loops' if you indent them

VB

FOR X = 1 to LINES
    FOR Y = 1 to X
    
    NEXT Y
NEXT X

[/EDIT]