News  • Daily news  • Archived news Columns  • WildCard  • Qbasic Articles  • QB Comic! Learning center  • QB Books  • Qbasic Lessons!  • Qbasic FAQ  • Newbies Section  • Qbasic Tutorials
		.SELECT Statement Details.   QuickSCREEN      Details      Example      Contents      Index ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ SELECT Statement Details Syntax   SELECT CASE testexpression   CASE expressionlist1     [statementblock-1]   [CASE expressionlist2     [statementblock-2]] ...     [CASE ELSE     [statementblock-n]]   END SELECT     Argument            Description   testexpression      Any numeric or string expression.     statementblock-1,   The elements statementblock-1 to   statementblock-2,   statementblock-n consist of any number of   statementblock-n    statements on one or more lines.     expressionlist1,    These elements can have any of the three   expressionlist2     following forms:                           expression[,expression...]                         expression TO expression                         IS relational-operator expression   The following list describes the parts of an expressionlist:     Argument              Description   expression            Any numeric or string expression. The type of                         the expression must match the type of the                         testexpression.     relational-operator   Any of the following operators:                             Symbol    Meaning                           <         Less than                           <=        Less than or equal to                           >         Greater than                           >=        Greater than or equal to                           <>        Not equal                           =         Equal   If the testexpression matches the expressionlist associated with a CASE clause, then the statement block following that CASE clause is executed up to the next CASE clause or, for the last one, up to END SELECT.  Control then passes to the statement following END SELECT.   If you use the TO keyword to indicate a range of values, the smaller value must appear first. For example, the statements associated with the line CASE -1 TO -5 are not executed if the testexpresssion is -4.  The line should be written as CASE -5 TO -1.   You may use a relational operator only if the IS keyword appears. If CASE ELSE is used, its associated statements are executed only if the testexpression does not match any of the other CASE selections. It is a good idea to have a CASE ELSE statement in your SELECT CASE block to handle unforeseen testexpression values.   When there is no CASE ELSE statement, and no expression listed in the CASE clauses matches testexpression, program execution continues normally. No error occurs.   You may use multiple expressions or ranges in each CASE clause. For example, the following line is valid:     CASE 1 TO 4, 7 TO 9, 11, 13, IS > MaxNumber%   You may also specify ranges and multiple expressions for strings:     CASE "everything", "nuts" TO "soup", TestItem$   CASE matches strings that are exactly equal to everything, the current value of TestItem$, or that fall between nuts and soup in alphabetical order.   Strings are evaluated according to the ASCII values of their characters. Lower-case letters have larger ASCII values than upper-case, therefore     nuts > Nuts > NUTS   If an expression appears in more than one CASE clause, only the statements associated with the first appearance of the expression are executed.   SELECT CASE statements may be nested. Each SELECT CASE statement must have a matching END SELECT statement.