Difference between revisions of "Recital Variables and Constants"
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local cVar3 | local cVar3 | ||
| − | PUBLIC variables are globally visible, they are accessible and can be changed from any part of an application. If the application is run from the Interactive Prompt, then any public variables can still be accessed even after the application ends. Any variables created at the Interactive Prompt are automatically created as public variables. | + | [[PUBLIC]] variables are globally visible, they are accessible and can be changed from any part of an application. If the application is run from the Interactive Prompt, then any public variables can still be accessed even after the application ends. Any variables created at the Interactive Prompt are automatically created as public variables. |
| − | PRIVATE variables are only visible within the declaring module (program, procedure, User Defined Function) and any modules called by that declaring module. Any variables accessed within a module that are not pre-declared are automatically created as private variables. When the module returns, then all of the memory variables and arrays that were declared by the PRIVATE command are released. | + | [[PRIVATE]] variables are only visible within the declaring module (program, procedure, User Defined Function) and any modules called by that declaring module. Any variables accessed within a module that are not pre-declared are automatically created as private variables. When the module returns, then all of the memory variables and arrays that were declared by the PRIVATE command are released. |
| − | LOCAL variables are only visible within the declaring module and are released when the module returns. LOCAL variables differ from PRIVATE variables in that a LOCAL variable is not visible to lower level procedures or functions. | + | [[LOCAL]] variables are only visible within the declaring module and are released when the module returns. LOCAL variables differ from PRIVATE variables in that a LOCAL variable is not visible to lower level procedures or functions. |
====Assigning a Value to a Variable==== | ====Assigning a Value to a Variable==== | ||
Revision as of 13:17, 21 October 2009
Contents
Recital Variables and Constants
An Introduction to Recital Variables
Naming and Creating a Variable
Memory variable names must begin with a letter (A-Z, a-z) or an underscore (-), followed by any combination of letters, digits or underscores. The variable name can be of any length, but only the first ten characters are significant, so these must be unique. Recital ignores the case of letters, so m_var, M_VAR, and m_VaR would all be treated as the same memory variable name. The name given to a memory variable has no bearing on the type of data that is, or can be, stored in it. In fact, the type of data stored in a particular variable can be changed at any time, although this needs to be carefully controlled so that inappropriate operations are not attempted. e.g.
m_var = 1234 m_var = ‘a character value’ ? m_var + 100
Values can be assigned to memory variables without those memory variables having been pre-declared, but it is generally accepted that the pre-declaration of memory variables is good programming practice. Variables can be declared as PUBLIC, PRIVATE or LOCAL and will be initialized as a logical false (.F.).
public cVar1 private cVar2 local cVar3
PUBLIC variables are globally visible, they are accessible and can be changed from any part of an application. If the application is run from the Interactive Prompt, then any public variables can still be accessed even after the application ends. Any variables created at the Interactive Prompt are automatically created as public variables.
PRIVATE variables are only visible within the declaring module (program, procedure, User Defined Function) and any modules called by that declaring module. Any variables accessed within a module that are not pre-declared are automatically created as private variables. When the module returns, then all of the memory variables and arrays that were declared by the PRIVATE command are released.
LOCAL variables are only visible within the declaring module and are released when the module returns. LOCAL variables differ from PRIVATE variables in that a LOCAL variable is not visible to lower level procedures or functions.
