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Causes of run-time errors for expressions

At run time the application logs errors about invalid expressions to diagnostics under these circumstances:

  • The expression is too large. The maximum compiled size for an expression is 8 KB.
  • The expression attempts to compare a string to a number.
  • The expression attempts to perform an invalid operation on a string. You can only use string tags as operands with the plus (+) arithmetic operator and with relational operators.
  • Adding two strings yields a long string. The maximum string length is 82 characters.
  • The expression contains an invalid instruction. In this case, the probable cause is file corruption. Recreate the run-time project.
  • A tag in the expression is uninitialized, the value is too old (stale), or the value is in error.
  • The expression attempts to perform an invalid operation on a floating point number. You cannot perform modulus or bitwise operations on floating point numbers.
  • The expression attempts to divide by zero or perform modulus with zero in the denominator.
  • The expression attempts to calculate the square root of a negative number.

See also

About expressions

The Expression editor

String tags in expressions