+ Operator

Description

Used to sum two numbers.

Syntax

result = expression1+expression2

The + operator syntax has these parts:

Part Description
result Any numeric variable.
expression1 Any expression.
expression2 Any expression.


Remarks

Although you can also use the + operator to concatenate two character strings, you should use the & operator for concatenation to eliminate ambiguity and provide self-documenting code.

When you use the + operator, you may not be able to determine whether addition or string concatenation will occur. If at least one expression is not a Variant, the following rules apply:

If Then
Both expressions are numeric data types (Byte, Boolean, Integer, Long, Single, Double, Date, or Currency) Add.
Both expressions are String Concatenate.
One expression is a numeric data type and the other is any Variant (except Null) Add.
One expression is a String and the other is any Variant (except Null) Concatenate.
One expression is an Empty Variant Return the remaining expression unchanged as result.
One expression is a numeric data type and the other is a String A Type mismatch error occurs.
Either expression is Null result is Null.


If both expressions are Variant expressions, the underlying type of the expressions determines the behavior of the + operator in the following way:

Both Variant expressions are numeric Add.
Both Variant expressions are strings Concatenate.
One Variant expression is numeric and the other is a string Add.


For simple arithmetic addition involving only expressions of numeric data types, the data type of result is usually the same as that of the most precise expression. The order of precision, from least to most precise, is Byte, Integer, Long, Single, Double, and Currency. The following are exceptions to this order:

  • When a Single and a Long are added together, the data type of result is converted to a Double.
  • When the data type of result is a Long, Single, or Date variant that overflows its legal range, result is converted to a Double variant.
  • When the data type of result is a Byte variant that overflows its legal range, result is converted to an Integer variant.
  • When the data type of result is an Integer variant that overflows its legal range, result is converted to a Long variant.
  • When a Date is added to any data type, the data type of result is always a Date.

Note The order of precision used by addition and subtraction is not the same as the order of precision used by multiplication.

If one or both expressions are Null expressions, result is Null. If both expressions are Empty, result is an Integer. However, if only one expression is Empty, the other expression is returned unchanged as result.

See Also

Operator Precedence.

Example

This example uses the + operator to sum numbers. The + operator can also be used to concatenate strings, however, to eliminate ambiguity, you should use the & operator instead. If the components of an expression created with the + operator include both strings and numerics, the arithmetic result is assigned. If the components are exclusively strings, the strings are concatenated.


MyNumber = 2 + 2                ' Returns 4.= 4257.04 + 98112    ' Returns 102369.04.= "34": Var2 = 6        ' Initialize mixed variables.= Var1 + Var2        ' Returns 40.= "34": Var2 = "6"        ' Initialize variables with strings.= Var1 + Var2        ' Returns "346" (string concatenation).