Reading Legacy Code: Strings and Numbers

You will encounter these patterns in older BBj codebases. Each section shows the legacy approach and its modern equivalent.

Uppercase Keywords and Line Numbers

You may see this in 1st Gen (BBx) code:

rem Legacy: uppercase keywords with line numbers
0010 LET A$ = "HELLO WORLD"
0020 PRINT LEN(A$)
0030 PRINT CVS(A$, 32)
0040 RELEASE

The modern equivalent:

rem Modern: lowercase keywords, no line numbers
a$ = "Hello World"
print len(a$)
print cvs(a$, 32)
release

BBj is case-insensitive for keywords -- PRINT and print compile identically. The LET keyword for assignments is optional in modern BBj and almost never used. Line numbers are also optional. Modern convention uses lowercase keywords and no line numbers for readability.

String Searching Before MASK()

You may see this in 1st Gen and 2nd Gen code:

rem Legacy: validate digits using POS() loop
valid% = 1
for i = 1 to len(input$)
    if pos(input$(i,1) = "0123456789") = 0 then
        valid% = 0
        break
    fi
next i

The modern equivalent:

rem Modern: one MASK() call with regex
if mask(input$, "^[0-9]+$") then valid% = 1 else valid% = 0

MASK() was added in BBj and provides Perl 5 regular expression matching. Before it existed, all pattern matching required nested POS() calls and character-by-character loops. When maintaining legacy code, these multi-line POS() validation patterns are candidates for simplification with MASK().

Inline PRINT Formatting Masks

You may see this in 1st Gen and 2nd Gen code:

rem Legacy: inline PRINT mask
print (0)"Price: $##,##0.00",total
print (0)"Qty:   ###",qty

The modern equivalent:

rem Modern: STR() for formatting, separate from output
print "Price: ", str(total:"$##,##0.00")
print "Qty:   ", str(qty:"###")

The mask syntax itself has not changed -- $##,##0.00 works the same way in both approaches. The difference is where the formatting happens. Legacy code embeds the mask directly in the PRINT statement, while modern code uses STR() to format the value first. STR() is preferred because it separates formatting from output, making the code easier to read and the formatted value reusable.

MID$/LEFT$/RIGHT$ Functions

You may see this in code migrated from other BASIC dialects:

rem Migrant pattern: BASIC dialect string functions
rem These do NOT exist in BBj
rem x$ = MID$(a$, 3, 5)
rem x$ = LEFT$(a$, 5)
rem x$ = RIGHT$(a$, 3)

The BBj equivalent:

rem BBj: substring notation (1-based)
a$ = "Hello World"
x$ = a$(3, 5)
y$ = a$(1, 5)
z$ = a$(len(a$) - 2)

BBj does not use MID$, LEFT$, or RIGHT$ functions. These are common in Microsoft BASIC dialects (GW-BASIC, QBasic, Visual Basic). BBj has always used its own substring notation: a$(position, length) for extraction and a$(position) for "from position to end." If you encounter these function names in documentation or code comments, they refer to other BASIC dialects, not BBj.