SAS Variables in Expressions

Definition

variable: is a set of data values that describe a given characteristic. A variable can be used in an expression.

Automatic Numeric-Character Conversion

If you specify a variable in an expression, but the variable value does not match the type called for, SAS attempts to convert the value to the expected type. SAS automatically converts character variables to numeric variables and numeric variables to character variables, according to the following rules:

If you use a character variable with an operator that requires numeric operands, such as the plus sign, SAS converts the character variable to numeric.
If you use a comparison operator, such as the equal sign, to compare a character variable and a numeric variable, the character variable is converted to numeric.
If you use a numeric variable with an operator that requires a character value, such as the concatenation operator, the numeric value is converted to character using the BEST12. format. Because SAS stores the results of the conversion beginning with the right-most byte, you must store the converted values in a variable of sufficient length to accommodate the BEST12. format. You can use the LEFT function to left-justify a result.
If you use a numeric variable on the left side of an assignment statement and a character variable on the right, the character variable is converted to numeric. In the opposite situation, where the character variable is on the left and the numeric is on the right, SAS converts the numeric variable to character using the BESTn. format, where n is the length of the variable on the left.

When SAS performs an automatic conversion, it prints a note in the SAS log informing you that the conversion took place. If converting a character variable to numeric produces invalid numeric values, SAS assigns a missing value to the result, prints an error message in the log, and sets the value of the automatic variable _ERROR_ to 1.

Note: You can also use the PUT and INPUT functions to convert data values. These functions can be more efficient than automatic conversion. See The Concatenation Operator for an example of the PUT function. See SAS Language Reference: Dictionary for more details on these functions. [cautionend]

For more information on SAS variables, see SAS Variables or the SAS Language Reference: Dictionary.

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