- Not all operators are valid with all types of comparisons. When comparing strings, If, =, /=, >=, <= are valid, but not <. No error results, but the accuracy of the results can be affected.
- For strings, the standard wild-card characters listed in Wild-Card Characters are valid. For example, if the expression (IF (= .LAYER ELEC*) EDISON) is placed in the condition, all objects in the query on layers beginning with ELEC are displayed on the layer EDISON. In addition, the operators = and /= are valid with wild cards.
- For real numbers less than one, enter all decimal values with a leading zero; that is, enter .001 as 0.001.
- When nil is a possible parameter, AutoCAD Map 3D toolset uses zero.
- The expression evaluator deals only in strings; it does not distinguish between strings and numerics. The expression evaluator converts strings to their numeric values for math operations and converts the results back to strings.
- If you use variables set using AutoLISP, you must precede the variable with an exclamation point (!).
- To keep a space within a string, enclose the string in quotation marks. For example, "this string" evaluates as one string, with a space between the two words. Without the quotation marks, this string evaluates as two separate strings. The expression evaluator ignores quotation marks.
- You must enclose named objects with spaces in the name in parentheses when used in evaluator functions. These objects include layers, blocks, hatches, and linetypes.
- The following expressions handle a maximum of three arguments: +, –, *, /, AND, OR, STRCAT, =, and /=. All other expressions handle one or two arguments. If you use +, –, *, or /, you must supply more than one argument. For example, (+ 5 6) evaluates to 11; (+ 5 3 2) evaluates to 10.
- An expression evaluates numbers with scientific notation in compound simple expressions. For example, (+ 1e+001 1) evaluates to 11.0000; 1e+001 evaluates to 10.0.
- AutoCAD Map 3D toolset evaluates pi only in compound expressions; the program treats pi as a string in simple expressions. For example, (STRCAT pi "_%") evaluates to 3.14%; pi by itself evaluates to "pi."
- You can specify color using ACI, True Color, or Color Book color values.