Difference between revisions of "PARAMETERS"
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==Class== | ==Class== | ||
Applications | Applications | ||
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<code lang="recital"> | <code lang="recital"> | ||
procedure add | procedure add | ||
| − | parameters para1, para2 | + | parameters para1, para2 |
| − | result = para1+ para2 | + | result = para1 + para2 |
return | return | ||
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[[Category:Documentation]] | [[Category:Documentation]] | ||
[[Category:Commands]] | [[Category:Commands]] | ||
| + | [[Category:Applications]] | ||
| + | [[Category:Applications Commands]] | ||
| + | [[Category:Memory Variables]] | ||
| + | [[Category:Memory Variables Commands]] | ||
Revision as of 13:47, 4 June 2009
Class
Applications
Purpose
Declare formal parameters to a procedure or program
Syntax
PARAMETERS <parameter list>
See Also
&, DECLARE, DO, LOCAL, LPARAMETERS, PRIVATE, PROCEDURE, PUBLIC, SET CLIPPER, SET PROCEDURE
Description
The PARAMETERS command declares a list of private memory variables or arrays, and assigns them the values of the actual parameters specified on a DO <program | procedure> WITH command. The parameters are initially declared as logicals with the value .F.. The PARAMETERS command must be the first executable command in a procedure or program. The PCOUNT() function is used to determine how many parameters were passed.
Parameters may be passed which are memory variables (i.e. they are not part of an expression). The contents of these memory variables will be updated when the procedure or program returns. This type of parameter passing is known as call by reference. This is the default for Recital/4GL with PROCEDURES and PROGRAMS. The '@' character may be placed in front of the memory variable name in User Defined Functions (UDF), so that they are called by reference.
If you do not wish the parameters to be modified by the called PROCEDURE or PROGRAM, you should enclose the memory variable in round brackets. This type of parameter passing is known as call by value. Any expressions that you specify as parameters are always call by value parameters. The default passing of parameters with User Defined Functions (UDF) is call by value. If COMPATIBLE is set ON then the parameters will be passed by reference. The limit to the number of parameters that you can pass is 40.
The private memory variables created by the PARAMETERS command are always released when the procedure or program returns. If CLIPPER is set ON and not all parameters are passed, the variables in the PARAMETERS command not passed will be defined as type 'U' instead of .F..
Example
procedure add parameters para1, para2 result = para1 + para2 return private result do add with 10, 40 ? result 50
Products
Recital Database Server, Recital Mirage Server, Recital Terminal Developer
