1 files changed, 30 insertions, 0 deletions
diff --git a/cpp/023length b/cpp/023length
new file mode 100644
index 00000000..9d3bb714
--- /dev/null
+++ b/cpp/023length
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+//: Recipe to compute the length of an array.
+
+:(scenario "array_length")
+recipe main [
+  1:integer <- copy 3:literal
+  2:integer <- copy 14:literal
+  3:integer <- copy 15:literal
+  4:integer <- copy 16:literal
+  5:integer <- length 1:array:integer
+]
++run: instruction main/4
++mem: storing 3 in location 5
+
+:(before "End Primitive Recipe Declarations")
+LENGTH,
+:(before "End Primitive Recipe Numbers")
+Recipe_number["length"] = LENGTH;
+:(before "End Primitive Recipe Implementations")
+case LENGTH: {
+  reagent x = canonize(instructions[pc].ingredients[0]);
+  if (x.types[0] != Type_number["array"]) {
+    raise << "tried to calculate length of non-array " << x.to_string() << '\n';
+    break;
+  }
+  vector<int> result;
+//?   cout << "length: " << x.value << '\n'; //? 1
+  result.push_back(Memory[x.value]);
+  write_memory(instructions[pc].products[0], result);
+  break;
+}