A+ Control Statements

• In General

  • Two Way Selctor is a Tradition IF...THEN...ELSE Statement
  • Pretest Loop is a WHILE
  • Post Test Loop is a LOOP...UNTIL
  • All Control Statements Use Labels to Eliminate Confusion in Nesting.
    • Probably the most common bug in programming is mismatched or incorrectly nested control statements
    • The usual way of interpreting a control statement is a rule and not a grammar. A+ takes a grammatical approach.

• XML

• control::= selector | loop.

• selector ::=label “IF” expression “THEN” eoln statementlist O(“ELSEOF” label eoln statementlist) “ENDOF” label.

• loop::= label “WHILE” expression eoln statementlist “ENDOF” label | label “LOOP” eoln statementlist “ENDOF” label “UNTIL” expression.

• label::=”a”..”z”

Notes: