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Addition Operator (+)

Visual Studio 2010

Adds the value of one numeric expression to another or concatenates two strings.

Copy 
expression1 + expression2

expression1

Any expression.

expression2

Any expression.

The type of the expressions determines the behavior of the + operator.

If

Then

Result Type

Both expressions are char

Concatenate

String

Both expressions are numeric

Add

numeric

Both expressions are strings

Concatenate

String

One expression is char and the other is numeric

Add

char

One expression is char and the other is a string

Concatenate

String

One expression is numeric and the other is a string

Concatenate

String

For concatenation, numbers are coerced into a string representation of the numeric value, and chars are considered to be strings of length 1. For addition of a char and a number, the char is coerced into a numeric value, and the two numbers are added.

NoteNote

In scenarios where type annotation is not used, numeric data may be stored as a strings. Use explicit type conversion or type annotate variables to ensure that the addition operator does not treat numbers as strings, or vice versa.

The following example illustrates how the addition operator processes expressions of different types.

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var str : String = "42";
var n : double = 20;
var c : char = "A";  // the numeric value of "A" is 65
var result;
result = str + str;  // result is the string "4242"
result = n + n;      // result is the number 40
result = c + c;      // result is the string "AA"
result = c + n;      // result is the char "U"
result = c + str;    // result is the string "A42"
result = n + str;    // result is the string "2042"
// Use explicit type coversion to use numbers as strings, or vice versa.
result = int(str) + int(str);    // result is the number 84
result = String(n) + String(n);  // result is the string "2020"
result = c + int(str);           // result is the char "k"
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