Local symbol definition

Symbols defined inside a function body are only visible to the function.

Purpose of local symbols

Local function symbols are part of and only to be used in the function body. They are created and initialized when the function is invoked. They are dropped when the function terminates.

Defining local symbols

Inside the body of a function, you can define language elements that will only be visible for the function code:

local constants with the CONSTANT instruction,
local user-defined types with the TYPE instruction,
local variables with the DEFINE instruction.

FUNCTION check_customer( cust_id INTEGER )
  CONSTANT c_max = 1000 -- local constant
  TYPE t_cust RECORD LIKE customer.* -- local type
  DEFINE found BOOLEAN -- local variable
  ...
END FUNCTION

Function arguments and local symbols must use different names, it is not possible to define a local variable with the same name as a function parameter:

FUNCTION func_a(x INTEGER)
   DEFINE x INTEGER
| The symbol 'x' has been defined more than once.
| See error number -4319.
   LET x = 1
END FUNCTION

Scope of local symbols

Local function symbols are not visible in other program blocks. Global or module variable can use the same name as a local variable: The global or module variable is not visible within the function scope of the local variable using the same name.

DEFINE x INTEGER   -- Declares a module variable

FUNCTION func_a()
  DEFINE x INTEGER -- Declares a local variable
  LET x = 123      -- Assigns local variable
END FUNCTION

FUNCTION func_b()
  LET x = 123     -- Changes the module variable
END FUNCTION

To increase code readability, consider using different names for global, module and local function symbols. A common practice is to use prefixes for global (g_) and module (m_) variables.