sfmc.guide
Engagement Next
⌘K

Concat

Joins two or more values into a single string. Runtime-proven on a live Marketing Cloud Engagement CloudPage — including the one-argument form the reference never mentions and the boolean values that vanish without a trace.

Next
Runtime verified Test scripts included

Syntax

Concat(string1, string2[, stringN, ...])  →  string

Parameters

Name Type Required Description
string1 string | number | date Yes First value to join
string2 string | number | date No Second value to join
stringN string | number | date No Any number of further values

There is no upper bound on the argument count.

Example

%%[
  VAR @greeting
  SET @greeting = Concat("Hello ", AttributeValue("FirstName"), "!")
]%%
%%=v(@greeting)=%%

With a first name of Ada, renders Hello Ada!.

Nothing is inserted between the values, so a separator has to be an argument of its own:

%%[
  VAR @label
  SET @label = Concat("Order", " ", "#", 4711)
]%%

Yields Order #4711.

Return value

string — every supplied value converted to text and joined in order, with no separator inserted.

The result is arbitrary text, so there is no closed set of sentinel values to test for.

Behaviour

One argument is enough. Concat("only") returns HTTP 200 and echoes the argument back unchanged. Our own catalog previously encoded a minimum of two arguments; it has been corrected to one. This is summarised on Differs from official docs.

Zero arguments abort the page. A bare Concat() aborts the CloudPage with HTTP 422 — the surrounding marker line never renders. So the real minimum is one, not zero.

Genuinely variadic. Two, three, twelve and twenty arguments were all accepted and joined in order: Concat("Hello", "World") gives HelloWorld, and a twenty-argument call gives abcdefghijklmnopqrst.

Numbers are joined by their string form. Concat(12, 3.5) gives 123.5 — no arithmetic happens, and no separator is inserted between the operands.

Date values are stringified. Concat(Now(), "X") renders the formatted date followed directly by the X.

Empty strings contribute nothing. Joining empty strings gives an empty result rather than an error.

Booleans are swallowed silently. Concat(true, false) returns HTTP 200 with an empty result — neither operand contributes anything. Nothing coherent about the boolean survives, so this is a rejection rather than boolean support, and the parameter types stay string | number | date. The same happens across the whole String family; see Differs from official docs. Convert a boolean to text yourself before joining it.

Show test script
%%[
  VAR @b
  SET @b = RequestParameter("b")

  /* safe sweep: everything here is accepted and can share one request */
  IF @b == "safe" THEN
    OutputLine(Concat("C2=[", Concat("Hello", "World"), "]"))
    OutputLine(Concat("C3=[", Concat("a", "-", "b"), "]"))
    OutputLine(Concat("C12=[", Concat("1","2","3","4","5","6","7","8","9","A","B","C"), "]"))
  ENDIF

  /* twenty arguments: still accepted */
  IF @b == "c20" THEN
    OutputLine(Concat("C20=[", Concat("a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t"), "]"))
  ENDIF

  /* one argument: HTTP 200, the value comes back unchanged */
  IF @b == "c1" THEN
    OutputLine(Concat("--- c1 start ---"))
    OutputLine(Concat("C1=[", Concat("only"), "]"))
    OutputLine(Concat("--- c1 done ---"))
  ENDIF

  /* zero arguments: page aborts with HTTP 422, no marker renders */
  IF @b == "c0" THEN
    OutputLine(Concat("--- c0 start ---"))
    OutputLine(Concat("C0=[", Concat(), "]"))
  ENDIF

  /* numbers are stringified, not added */
  IF @b == "cn" THEN
    OutputLine(Concat("CN=[", Concat(12, 3.5), "]"))
  ENDIF

  /* date values are stringified */
  IF @b == "cd" THEN
    OutputLine(Concat("CD=[", Concat(Now(), "X"), "]"))
  ENDIF

  /* booleans: HTTP 200 but nothing renders between the brackets */
  IF @b == "cb" THEN
    OutputLine(Concat("CB=[", Concat(true, false), "]"))
  ENDIF

  /* empty strings join to an empty result */
  IF @b == "empty" THEN
    OutputLine(Concat("CE=[", Concat("", ""), "]"))
  ENDIF
]%%

Availability

Platform Available
Marketing Cloud Engagement Yes
Marketing Cloud Next Yes, from API 67.0

See also