Variables and Math

A variable is a named box in memory. In FreeBASIC you create one with DIM, and you say what type of value the box holds. The type matters because this is a compiled language: the compiler uses it to decide how much memory the box needs and which operations make sense on it.

DIM age AS INTEGER       ' whole numbers
DIM price AS DOUBLE      ' numbers with a decimal point
DIM city AS STRING       ' text

age = 36
price = 19.99
city = "Dhaka"

You can declare and assign in one line, and declare several variables at once:

DIM score AS INTEGER = 100
DIM a AS INTEGER, b AS INTEGER

Why declaration is mandatory

FreeBASIC's default dialect refuses to touch a variable you never declared. That sounds strict; it is protection:

DIM total AS INTEGER
total = 10
totl = total + 5     ' COMPILE ERROR: variable not declared

The misspelled totl is caught at compile time. Old BASICs silently created a brand-new variable worth 0 and carried on — the most infamous bug generator of the 8-bit era.

The suffix trap (legacy syntax)

In old listings you will see type suffixes instead of AS: count% for an integer, total# for a double, a trailing $ for a string. Recognize them — but do not write them. The default FreeBASIC dialect used here rejects them:

DIM count%             ' COMPILE ERROR: suffixes only exist in the old -lang qb dialect
DIM count AS INTEGER   ' the modern way

Arithmetic

PRINT 7 + 2     ' 9
PRINT 7 - 2     ' 5
PRINT 7 * 2     ' 14
PRINT 7 / 2     ' 3.5   -- / ALWAYS gives a floating-point result
PRINT 7 \ 2     ' 3     -- \ is integer division (drops the remainder)
PRINT 7 MOD 2   ' 1     -- remainder
PRINT 2 ^ 10    ' 1024  -- exponent

The classic trap is / versus \. If you want a whole-number result, \ (backslash) is the operator — 7 / 2 is 3.5 even when both sides are INTEGERs.

How PRINT shows numbers

On this platform PRINT 7 outputs exactly 7 and a newline — no padding. Trivia with consequences: 1980s BASICs (and FreeBASIC's -lang qb compatibility mode) print a leading space before positive numbers. The default dialect does not, and the grader's expected outputs are written for this no-space behavior.

Strings

& glues strings together — and it converts numbers to text automatically:

DIM greeting AS STRING
greeting = "Hello, " & city & "!"
PRINT greeting                     ' Hello, Dhaka!
PRINT "Length: " & LEN(greeting)   ' Length: 13
PRINT UCASE(city)                  ' DHAKA
PRINT LCASE(city)                  ' dhaka

+ also concatenates, but only when both sides are strings — "Age: " + 36 is a compile-time type error, while "Age: " & 36 just works. Habit worth building: use & for text.

Reading two values

INPUT "", x reads one value per line of input; the "" suppresses the ? prompt that would otherwise pollute your output:

DIM a AS INTEGER, b AS INTEGER
INPUT "", a
INPUT "", b

That is exactly what your exercise starter already does.

Your exercise

Read two integers (the starter handles that) and print their sum. Replace the ' PRINT ... comment with one statement.

• Print only the number. PRINT a + b for inputs 3 and 4 outputs exactly 7 — the grader rejects decorations like sum = 7 or echoing the inputs back.
• The hidden test feeds a negative value (-5 and 5 must print 0). Plain addition already handles it — no IF needed.
• One PRINT, run once. The newline after 7 comes from PRINT itself.