BASIC Overview

This general overview includes information on these topics:

Attribute Count Expression	Any numeric constant or any arithmetic, logical, or string expression that evaluates to a valid numeric value, used to reference an attribute count within statements, functions, and arrays or string variable.
Arithmetic Expressions	Perform mathematical calculations on any set of operand expressions.
Arithmetic Operators	Add, subtract, multiply and divide numeric operands in arithmetic expressions.
Arrays	Defines and describes dynamic and dimensioned arrays.
Array References	Discusses referencing arrays in BASIC programs.
Array Variable	Discusses array variables, which are used to reference dynamic and dimensioned arrays.
Arrays and Relational Expressions	Discusses using relational expressions to compare elements in dimensioned and dynamic arrays.
Assignment	Discusses assigning the value of an expression to a variable.
Boolean Evaluation	Discusses the use of boolean expressions.
Compile Stamps	Discusses compile stamp items, which contain descriptive internal information about programs compiled for BASIC.
Conversion Expression	Discusses conversion expressions, which are any functions that evaluate to a valid processing code (conversion).
Data Representation	Discusses to the data types employed in BASIC.
Default File Variables	Discusses the use of default file variables.
Error Condition	Discusses the error condition process state that occurs when a program encounters a condition that cannot be resolved.
File Variable	Discusses using file variables to access a file that was being previously opened in a BASIC program.
Format Strings	Discusses using format strings to format numeric and nonnumeric strings.
Functions	Discusses the use of functions in BASIC.
Global Common	Discusses the global common, which is a named BASIC variable space used to store variables and arrays in the identified area that is only initialized at logon.
ID Expression	Discusses the ID expression, which is a string expression that evaluates to an item-ID, for use in all types of read and write statements.
Logical Expressions	Discusses logical expressions, which are the result of applying logical (Boolean) operators to relational or arithmetic expressions.
Masking	Discusses masking, which is the process of formatting expressions using numeric masks and format masks.
Named Common	Discusses the named common, which is a global, common, BASIC variable space used to store variables and arrays in the area identified by ID.
Nonfatal Error Condition	Discusses the nonfatal error condition, which is a type of error that occurs when a BASIC program encounters a condition that is resolved by the BASIC run-time package, although not to the specific need of the program line of code.
Nuclear Tokens	Discusses nuclear tokens, which is the idea that any function or expression can itself be an argument of another function or expression.
Null Evaluation	Discusses null evaluation, which represents an empty string or decimal zero value depending on the context, string, or arithmetic operation.
Numeric Expressions	Discusses the numeric expression, which is any expression that evaluates to a number.
Operators	Discusses operators, which are reserved characters (and combinations of adjacent characters) and can be referenced individually by their respective symbol.
Precedence	Discusses precedence, which is the set of rules imposed upon the evaluation of components of an expression that are not otherwise overridden by the presence of parentheses.
Relational Expressions	Discusses relational expressions, which evaluate to 1 if the relation is true, and evaluate to 0 if the relation is false.
Relational Operators	Discusses relational operators, which are used to compare both strings and/or numerics.
Reserved Characters	Discusses the characters that are reserved for special purposes in BASIC.
Reserved Words	Discusses the words that are reserved for special purposes in BASIC.
Retrieval Locks	If a BASIC program is run by a user that does not have retrieval or update privileges (for a file that does and is opened in the program), and then attempts to read and/or write to that file, the program terminates with an error message.
Subvalue Count Expressions	Discusses the use of retrieval locks in BASIC.
Statement Blocks	Discusses the statement block, which is one or more statements that follow a BASIC decision-path related token such as, but not limited to, then, else, locked, and onerr.
Statement Labels	Discusses statement labels, whach are used as the destinations of goto or gosub statements.
Statements and Functions	Describes the differences between statements and functions in BASIC and provides working definitions of variables, constants, labels, spaces, and program formatting.
String Expressions	Discusses the string expression, which is any expression that evaluates to, or can be converted to a string of characters.
Substrings	Discusses the substring, which is a set of characters that makes up part of a whole string.
Substring Expressions	Discusses substring expressions, which extract or assign substrings by using the [ and ] characters.
Symbol Table	Discusses the symbol table, which is used by the BASIC debugger to reference symbolic variables.
then/else Statement Blocks	Discusses statement blocks, which are used in conjunction with conditional statements.
Value Count Expression	Discusses the value count (vc) expression, which is an expression that evaluates to a valid value count.
Variables	Discusses variables, which store numbers, strings, file descriptors, or select lists and can change dynamically throughout the execution of the program.