Returns the element at the front of the queue without removing the element from the queue.


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Inputs/Outputs

  • cqueuern.png queue —

    queue is a reference to a queue.

    Use the Obtain Queue function to obtain a queue reference.
  • ci32.png timeout in ms (-1) —

    timeout in ms specifies the time, in milliseconds, that the function waits for an element to become available in the queue if the queue is empty.

    The default is –1, indicating never to time out.

    If the function waits timeout in ms and the queue remains empty, timed out? is TRUE.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • iqueuern.png queue out —

    queue out returns the reference to the queue unchanged.

  • istr.png element —

    element is the element at the front of the queue.

    This data type changes to match the subtype of queue.
  • ibool.png timed out? —

    timed out? returns TRUE if an element did not become available in the queue before the function timed out. timed out? also returns TRUE if this function encounters an error.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

    • Use the Dequeue Element function to return the element at the front of the queue and remove it from the queue. If the queue is empty, the function waits timeout in ms before timing out. If an element becomes available in the queue during the wait, the function returns the element and timed out? is FALSE. If queue becomes invalid (for example, the queue reference is released), the function stops waiting and returns error code 1122.