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LET

LET statement is used to assign a value or a set of values to a variable or a record.

Variable	A variable which is assigned a value
Expression list	One or more 4GL expressions that return the value which is assigned to the variable
Last member	The last record member of the specified set of members (if the "variable" represents the first member of the sequence)

A variable of any data type except for the object data types (e.g. WINDOW, FORM) can be assigned values with the help of the LET statement.

When a variable is declared with the help of the DEFINE statement, it has no value, but the memory space is allocated to it. There are two ways of initializing a variable (that is of assigning some value to it): the use of the INITIALIZE statement or the LET statement. Do not use a variable that has not been initialized in a 4GL expression, the value returned by such expression will hardly prove to be useful.

When 4GL encounters a LET statement, it evaluates the expression to the right of the equal sign (=) and then assigns it to the variable. The following example illustrates assignment of values to variables:

DEFINE a, b, c, d INT

LET a = 2

LET b = 5

LET c = a + b

LET d = NULL

Most of the 4GL built-in functions and operators can be used in the LET statement. The example below assigns an ASCII symbol to the variable. The displayed value will be "d":

DEFINE var1 CHAR(1)

LET var1 = ASCII 100

DISPLAY var1

You cannot assign individual values to a program record with the help of the LET statement, you cannot use the THRU/THROUGH keyword as well. However, you can assign values of one program record to another program record with the help of the .* notation, provided that the both records have the same number of members and the members are of compatible data types:

LET rec1.* = rec2.*

LET statement can be used to assign a value to a sub-string of CHAR, STRING or VARCHAR data type:

DEFINE full_name CHAR (30), fname CHAR (15)

LET full_name[1,15] = fname

The LET statement can assign only NULL values to the variables of the Large data types. To assign other values to such variables use the INTO clause in a SELECT, FOREACH, OPEN, or FETCH statement or pass the name of such variable as an argument to a function.