EVAL string-expression

Executes a single complete line of BASIC supplied in string-expression in the current program's context.

The string must form one valid statement line (for example PRINT "Hello", X = 10, PROCdemo).
On error, ERR$ is set to the error message and ERR is set to 1. Execution then continues at the statement after EVAL.
Recursive EVAL is not permitted (code running under EVAL may not call EVAL again).

Remarks: If you need a literal double quote inside the evaluated line, insert it using CHR$(34).; For example: EVAL "PRINT " + CHR$(34) + "Hello" + CHR$(34).

Print from a generated line

EVAL "PRINT " + CHR$(34) + "Hello from EVAL!" + CHR$(34)

Set a variable dynamically

NAME$ = "COUNT"
EVAL NAME$ + " = 42"
PRINT COUNT

Call a procedure

DEF PROCgreet
    PRINT "Greetings"
ENDPROC
 
EVAL "PROCgreet"

Error handling (ERR/ERR$ set, program continues)

ERR = 0
ERR$ = ""
 
EVAL "A = 1/0"
 
IF ERR <> 0 THEN
    PRINT "EVAL failed: "; ERR$
ENDIF

Provide exactly one statement; statement separators are not supported.
The evaluated line runs with access to the program's current variables, procedures, and functions.
Use EVAL for small, dynamic actions. For larger logic, write normal procedures/functions and call them directly.

See also: DEF, PROC, FN, ERR/ERR$