| .SUB...END SUB Statement Details. |
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| SUB...END SUB Statement Details |
|
| Syntax |
| SUB globalname[parameterlist][STATIC] |
| [statements] |
| [EXIT SUB] |
| [statements] |
| END SUB |
| |
| Argument Description |
| globalname A variable name up to 40 characters long. This name |
| cannot appear in any other FUNCTION or SUB |
| statement in the same program or the user library. |
| |
| parameterlist Contains the names of simple variables and arrays |
| passed to the subprogram when the SUB is invoked. |
| Each name is separated from the preceding name by |
| a comma. Note that these variables and arrays are |
| passed by reference, so any change to an argument's |
| value in the subprogram also changes its value in |
| the calling program. See below for a complete |
| description of the syntax. |
| |
| A SUB parameterlist has the following syntax: |
| |
| variable[()] [AS type][, variable[( )] [AS type]]... |
| |
| ž A variable is a BASIC variable name. Previous versions of BASIC |
| required the number of dimensions in parentheses after an array name. |
| In QuickBASIC, the number of dimensions is not required. |
| ž The argument type is the type of the variable. The type argument can be |
| INTEGER, LONG, SINGLE, DOUBLE, STRING, or a user-defined type. You may |
| not use a fixed-length string, or an array of fixed-length strings, as a |
| parameter. However, you may use a simple fixed-length string as an |
| argument in a CALL statement-QuickBASIC converts a simple fixed-length |
| string argument to a variable-length string argument before passing |
| the string to a SUB. |
| |
| A subprogram is a separate procedure, like a FUNCTION. However, |
| unlike a FUNCTION, a SUB cannot be used in an expression. |
| |
| SUB and END SUB mark the beginning and end of a subprogram. You may |
| also use the optional EXIT SUB statement to exit a subprogram. |
| |
| Subprograms are called by a CALL statement or by using the subprogram name |
| followed by the argument list. See the entry for the CALL statement. |
| |
| QuickBASIC subprograms can be recursive--they can call themselves |
| to perform a given task. See the second example below. |
| |
| The STATIC attribute indicates that all variables local to the SUB |
| are STATIC--their values are saved between calls. Using the STATIC |
| keyword slightly increases execution speed. STATIC is not usually |
| used with recursive subprograms. See the examples below. |
| |
| Any subprogram variables or arrays are considered local to that sub- |
| program, unless they are explicitly declared as shared variables in |
| a SHARED statement. |
| |
| You cannot define SUB procedures, DEF FN functions, or FUNCTION |
| procedures inside a SUB procedure. |
| |
| Note: You cannot use GOSUB, GOTO, or RETURN to enter or exit a |
| subprogram. |
