{
  "id": "programming.strings.plus-adds-before-concatenating",
  "uri": "https://open-misconceptions.github.io/miscon-data/m/programming.strings.plus-adds-before-concatenating",
  "uuid": "71cc8015-8e64-4cbf-aec0-1227ef5023f9",
  "version": "0.1.1",
  "status": "draft",
  "trust": "low",
  "title": "Plus adds numbers before it concatenates",
  "statement": "In an expression that mixes strings and numbers with +, the numbers are added together first and the string is attached afterwards.",
  "kind": "overgeneralization",
  "domain": "programming.strings",
  "about": [
    {
      "scheme": "Miscon",
      "uri": "https://open-misconceptions.github.io/miscon-data/c/programming.strings.concatenation-order"
    }
  ],
  "level_band": [
    "secondary",
    "undergraduate"
  ],
  "locale": "en",
  "evidence_patterns": [
    {
      "item_shape": "predict a left-to-right mixed concatenation",
      "signature": "adds the numeric operands regardless of their position",
      "example": {
        "item": "System.out.println(\"x\" + 1 + 2);",
        "expected": "x12",
        "response": "x3"
      }
    }
  ],
  "discriminators": {
    "vs_slip": "Consistent across items; the learner explains that 'plus means add'. A slip is one wrong prediction."
  },
  "relations": {
    "conflicts_with": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.strings.concatenation-order",
        "label": "Operators of equal precedence apply left to right"
      }
    ],
    "resolved_by": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.strings.concatenation-order",
        "label": "Operators of equal precedence apply left to right"
      }
    ]
  },
  "alignments": [
    {
      "scheme": "progmiscon",
      "code": "Java/ArithmeticPlusPrecedes",
      "uri": "https://progmiscon.org/misconceptions/Java/ArithmeticPlusPrecedes",
      "relation": "close-match"
    }
  ],
  "provenance": {
    "sources": [
      {
        "type": "inventory",
        "citation": "Chiodini, L., Moreno Santos, I., Gallidabino, A., Tafliovich, A., Santos, A. L., & Hauswirth, M. (2021). A curated inventory of programming language misconceptions. In Proceedings of the 26th ACM Conference on Innovation and Technology in Computer Science Education (ITiCSE '21), 380-386.",
        "doi": "10.1145/3430665.3456343",
        "url": "https://progmiscon.org/",
        "note": "Inventory consulted for the misconception name and scope only; progmiscon publishes no licence for its text, so Open Misconceptions' statements and examples are written independently."
      }
    ],
    "origin": "llm-drafted",
    "notes": "Drafted from the cited literature for the Open Misconceptions seed pack; statement, examples and discriminators are original text. Awaiting maintainer review."
  },
  "history": {
    "changelog": [
      {
        "version": "0.1.1",
        "date": "2026-09-05",
        "change": "Schema 0.2 migration: about/alignments carry a free-string scheme (corestandards.org URLs relabelled CCSS where present); trust computed from reviews[] (none yet, so low); no change to the statement or evidence."
      }
    ]
  },
  "license": "CC-BY-4.0"
}