Variables are dereferenced from left to right. Their values are substituted by the CI before the command is parsed or executed. String variables and constants can be concatenated to create a new string. Variables and strings can be joined to create a new variable value.
To concatenate a string variable with a prefix, place the prefix immediately before the exclamation point for the variable. If spacing is desired, the appropriate number of blanks must be inserted between the two values.
In the following example, the ECHO command is used to display a string made up of a string literal and the value of a variable that was set in a previous example. Note that the ECHO command requires explicit dereferencing to display the contents of a variable.
:ECHO GRADUATE: !CM_LAST_NAME
GRADUATE: SMITH
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If a dereferenced variable is enclosed in quotation marks, any dereferencing within the quotation marks is performed first. The following example demonstrates the difference between string substitution sequences.
:SETVAR VAR1 "ABC"
:SETVAR VAR 'hello'
:SETVAR A 1
:ECHO !VAR!A
hello1
:ECHO !"VAR!A"
ABC
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The first ECHO command is dereferenced from left to right. The value of the variable VAR (hello) is concatenated with the value of the variable A (1). No space was inserted between the two variables.
Since VAR!A in the second ECHO command is enclosed in quotes, the A is dereferenced first. The result, the variable name VAR1, is then dereferenced to its value ABC.
Variables can be loaded with a string value composed of other variables and strings. It is important to remember that the type of variable is defined by the data loaded into it. String data must be enclosed in quotes to define its type. In this way, explicit or recursive dereferencing must be performed to differentiate between variable names and strings. The following example creates a single variable for a name by combining the contents of the first and last name variables.
SETVAR CM_NAME "!CM_FIRST_NAME !CM_LAST_NAME"
SHOWVAR CM_NAME
CM_NAME = CAROL SMITH
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Expressions can also be used to set a variable value. The following example uses an algebraic equation to create the same result as in the previous example.
:SETVAR CM_NAME CM_FIRST_NAME + '' '' + CM_LAST_NAME
SHOWVAR CM_NAME
CM_NAME = CAROL SMITH
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Note that the string " " was added to the equation to maintain the proper spacing. Without this, adding the two variables would have concatenated the variable values.
