Member Avatar for krackhead

im taking a qbasic class and am having a very hard time on this program...here is the question:
Using the ASCII table and the CHR$ function, write a program that prints the following output using a nested for next loop:
A
AB
ABC
ABCD
ABCDE

--------------------------------------------------------------------
heres what I have so far...i keep getting a "type mismatch":

CLS
FOR Outer = 1 TO 5 STEP 1
FOR in = CHR$(65) TO CHR$(70) <------TYPE MISMATCH?????
PRINT in;
NEXT in
PRINT
NEXT Outer

what am i doing wrong? any help on this would be greatly appreciated....thanks :confused:

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  • Latest Post Latest Post by limpstarfish.flavouredwater

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the Type mismatch came from trying to use CHR$ in the FOR header. In QBasic, a FOR counter must be numeric; CHR$ returns a string. called this out, and was right that STEP 1 is implied. The trick is: loop over numbers, then convert each number to a character only when you print or build the line.

Here is a compact pattern that stays within the assignment (nested loops + CHR$) while avoiding type issues and the need for trailing semicolons:

DEFINT A-Z
base% = ASC("A")        ' start at ASCII A
FOR row% = 1 TO 5
    line$ = ""
    FOR col% = 0 TO row% - 1
        line$ = line$ + CHR$(base% + col%)
    NEXT col%
    PRINT line$
NEXT row%

Why this works:

  • The loop counters are integers (%), so FOR/NEXT is happy.
  • We compute characters from their codes only at the point of use.
  • Building line$ then printing once per row avoids relying on PRINT ...; to stay on the same line (as demonstrated), and it is easy to adapt.

Quick tips:

  • Prefer meaningful names over in (which can read like a keyword) to reduce confusion.
  • If you ever do print one character at a time, remember PRINT expr; stays on the same line, PRINT alone moves to the next line.
  • Using ASC("A") instead of 65 avoids magic numbers and makes intent clear.

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All 7 Replies

Member Avatar for Paladine

CLS
FOR Outer = 1 TO 5 STEP 1
FOR in = CHR$(65) TO CHR$(70) <------TYPE MISMATCH?????
PRINT in;
NEXT in
PRINT
NEXT Outer

what am i doing wrong? any help on this would be greatly appreciated....thanks :confused:

Well you are making it too difficult, the reason is write in front of you. CHR$(65) gives you what value?

...
Look at your ASCII Table if you don't know off hand.....

It is the Character A .

Now, look at your code. For in = CHR$(65) Stop right there!
If CHR$(65) gives a value of A and in is no doubt an integer value this is where you mismatch starts. You care comparing a Character String (albiet one character) to an Integer! So it unfortunately won't work. Can only compare like datatypes.

So some Conversion will be needed and I think you need to check your logic for this code....

Hope this helps.... If not let me know if you need more help!

Member Avatar for krackhead

I sill don't quite get it. Every time I try and switch it up to change values I get another error. I know im close but just cant figure it out. any suggestions?

Member Avatar for Phaelax

first of all, you don't need STEP, because the default step value is always 1. Secondly, A FOR statement is looking for an integer. CHR$() returns a character, which is not a number. Leave the CHR$() out of the FOR header. Look at the example below.

FOR outer = 1 to 5
	FOR in = 1 to outer
		PRINT CHR$(in+64)
	NEXT in
NEXT outer

Now lets run through the code step by step. First time through, "outer" will equal 1. So the following statement would actually be "FOR in = 1 to 1". "in" will equal 1 as well. Next line "PRINT CHR$(in+64)" This will be the same as "PRINT CHR$(65)" because "in" is 1. Now the loops starts back from the top. This time, "outer" will equal 2. So therefore, the following FOR statement would really mean "FOR in = 1 to 2". So that FOR loop will run through twice. The first time "in" being 1 and the second time "in" being 2. Which would print CHR$(1+64) and CHR$(2+64). And the pattern repeats until "outer" finally equals 5. Hope this helped you a little.

Member Avatar for sgtfubar

I just had a problem similar to this one. But I ended up making it harder than it really was. It all clicked when I figured out FOR is looking for integers instea of characters. Here's what I did:

CLS

FOR num = 32 TO 255
PRINT CHR$(num)
NEXT num

END

It can't get more simple than that.

Member Avatar for vegaseat

The code below should work if Qbasic works at all like BCX:

dim inner, outer

FOR outer = 1 to 5
FOR inner = 1 to outer
PRINT CHR$(inner + 64); ' stay on line
NEXT innner
PRINT ' new line feed
NEXT outer

Member Avatar for krackhead

The code below should work if Qbasic works at all like BCX:

dim inner, outer

FOR outer = 1 to 5
FOR inner = 1 to outer
PRINT CHR$(inner + 64); ' stay on line
NEXT innner
PRINT ' new line feed
NEXT outer

Well I do appreciate your help, but I took this class back in April and this is no longer useful to me. I got a B+........thanks anyway

Member Avatar for limpstarfish.flavouredwater

WELL U AIN'T PROBABLY GONNA WATCH THIS BUT I HAVE GOT A EASIER SOLUTION:

CLS
FOR I = 65 TO 69
FOR J = 65 TO I
D$=CHR(J)
PRINT D$;
NEXT J
PRINT
NEXT I
END

SEE SIMPLE AS THAT

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