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Syntax
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expression1
+
expression2
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Description
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Adds or concatenates two expressions.
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Comments
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Addition operates differently depending on the type of the two expressions:
|
|
|
If one
expression is
|
and the other
expression is
|
then
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Numeric
|
Numeric
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Perform a numeric add (see below).
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String
|
String
|
Concatenate, returning a string.
|
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|
Numeric
|
String
|
A runtime error is generated.
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Variant
|
String
|
Concatenate, returning a
String
variant.
|
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Variant
|
Numeric
|
Perform a variant add (see below).
|
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|
Empty
variant
|
Empty
variant
|
Return an
Integer
variant, value
0
.
|
|
|
Empty variant
|
Boolean variant
|
Return an
Integer
variant (value
0
or
-1
)
|
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Empty variant
|
Any data type
|
Return the non-
Empty
expression unchanged.
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Null
variant
|
Any data type
|
Return
Null
.
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Variant
|
Variant
|
If either is numeric, add; otherwise, concatenate.
|
|
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When using
+
to concatenate two variants, the result depends on the types of each variant at runtime. You can remove any ambiguity by using the
&
operator.
Numeric Add
A numeric add is performed when both expressions are numeric (i.e., not variant or string). The result is the same type as the most precise expression, with the following exceptions:.
|
|
|
If one
expression is
|
and the other
expression is
|
then
|
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Single
|
Long
|
Double
|
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Boolean
|
Boolean
|
Integer
|
|
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A runtime error is generated if the result overflows its legal range
Variant Add
If both expressions are variants, or one expression is numeric and the other expression is
Variant
, then a variant add is performed. The rules for variant add are the same as those for normal numeric add, with the following exceptions:
- If the type of the result is an
Integer
variant that overflows, then the result is a
Long
variant.
- If the type of the result is a
Long
,
Single
, or
Date
variant that overflows, then the result is a
Double
variant.
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Example
|
This example assigns string and numeric variable values and then uses the
+
operator to concatenate the strings and form the sums of numeric variables.
Sub Main()
i$ = "concatenate " + "strings!"
j% = 95 + 5 'Addition of numeric literals
k# = j% + j% 'Addition of numeric variable
MsgBox "You can " + i$
MsgBox "You can add literals or variables:" + Str(j%) + ", " + Str(k#)
End Sub
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See Also
|
& (Operator); Operator Precedence (topic)
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