CLI Variable Inspection¶

Learn how to inspect and monitor variables while debugging BASIC programs in the CLI.

Variable Inspection with PRINT¶

The CLI uses the PRINT statement for variable inspection during debugging:

PRINT A            ' Show single variable
PRINT A, B, C$     ' Show multiple variables
PRINT A; " = "; A  ' Show with label

Example session:

Ready
10 A = 5
20 B = 10
30 C$ = "Hello"
RUN
Ready
PRINT A
 5
Ready
PRINT A, B, C$
 5            10           Hello
Ready

Checking Variables During Debugging¶

Add PRINT statements to your program to inspect variables:

Ready
10 FOR I = 1 TO 5
15   PRINT "Loop I="; I; "A="; A    ' Debug output
20   A = A + I
30 NEXT I
40 PRINT "Sum:"; A
RUN
Loop I= 1 A= 0
Loop I= 2 A= 1
Loop I= 3 A= 3
Loop I= 4 A= 6
Loop I= 5 A= 10
Sum: 15
Ready
PRINT I, A         ' Check final values after program ends
 6            15

Variable Types¶

MBASIC has four variable types:

Integer Variables¶

A% = 100
PRINT A%
 100

Single-Precision (Float)¶

A! = 3.14159
PRINT A!
 3.14159

Double-Precision¶

A# = 3.141592653589793
PRINT A#
 3.141592653589793

String Variables¶

A$ = "Hello, World!"
PRINT A$
Hello, World!

Arrays¶

Arrays require DIM and can be inspected element by element:

10 DIM ARR(5)
20 FOR I = 1 TO 5
30   ARR(I) = I * 10
40 NEXT I
RUN
Ready
PRINT ARR(1), ARR(2), ARR(3)
 10           20           30

Variables Window (GUI UIs Only)¶

The CLI does not have a Variables Window feature. For visual variable inspection, use: - Curses UI - Full-screen terminal with Variables Window ({{kbd:toggle_variables:curses}}) - Tk UI - Desktop GUI with Variables Window - Web UI - Browser-based with Variables Window

Tips for Variable Inspection¶

Use meaningful names - Makes debugging clearer
PRINT with labels - PRINT "A="; A shows what you're checking
Add debug PRINT statements - Insert PRINT in your program to trace execution
Use TRON - Enable line tracing to see execution flow
Format output - Use semicolons and commas for readability

Example: Debugging with PRINT¶

Ready
10 FOR I = 1 TO 10
20   F = F + 1
25   PRINT "DEBUG: I="; I; "F="; F; "N="; N
30   N = N + F
40 NEXT I
50 PRINT "Result:"; N
RUN
DEBUG: I= 1 F= 1 N= 0
DEBUG: I= 2 F= 2 N= 1
DEBUG: I= 3 F= 3 N= 3
...
Result: 55
Ready
PRINT I, F, N         ' Check final values
 11           10           55

Common Patterns¶

Check Multiple Variables¶

PRINT "I="; I, "Sum="; S, "Avg="; A

Check Array Elements¶

PRINT A(1), A(2), A(3)

Check String Variables¶

PRINT "Name: "; N$; " Age: "; A%

Best Practices¶

PRINT after RUN - Variables persist after program ends
Use PRINT for quick checks - Faster than running the whole program
Label your output - Makes it clear what you're inspecting
Use TRON/TROFF - See execution flow to understand variable changes
Test in direct mode - Try expressions before adding to program