CODEWITHSUNDEEP
legacy-codeqbasic
G Shah
G Shah

Reputation: 2095

What are # and : used for in Qbasic?

I have a legacy code doing math calculations. It is reportedly written in QBasic, and runs under VB6 successfully. I plan to write the code into a newer language/platform. For which I must first work backwards and come up with a detailed algorithm from existing code.

The problem is I can't understand syntax of few lines:

Dim a(1 to 200) as Double
Dim b as Double
Dim f(1 to 200) as Double
Dim g(1 to 200) as Double

For i = 1 to N
 a(i) = b: a(i+N) = c
 f(i) = 1#: g(i) = 0#
 f(i+N) = 0#: g(i+N) = 1#
Next i

Based on my work with VB5 like 9 years ago, I am guessing that a, f and g are Double arrays indexed from 1 to 200. However, I am completely lost about this use of # and : together inside the body of the for-loop.

Upvotes: 1

Views: 336

Answers (2)

Ben Richards
Ben Richards

Reputation: 528

I haven't programmed in QBasic for a while but I did extensively in highschool. The # symbol indicates a particular data type. It is to designate the RHS value as a floating point number with double precision (similar to saying 1.0f in C to make 1.0 a single-precision float). The colon symbol is similar to the semicolon in C, as well, where it delimits different commands. For instance:

a(i) = b: a(i+N) = c

is, in C:

a[i] = b; a[i+N] = c;

Upvotes: 2

Blindy
Blindy

Reputation: 67388

: is the line continuation character, it allows you to chain multiple statements on the same line. a(i) = b: a(i+N) = c is equivalent to:

a(i)=b
a(i+N)=c

# is a type specifier. It specifies that the number it follows should be treated as a double.

Upvotes: 4

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