From f8498a8cb6006d718e699c98f4f35707fb792e61 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Paul=20T=2E=20K=C3=BChner?=
 <56360279+schnellerhase@users.noreply.github.com>
Date: Thu, 18 Jun 2026 11:34:15 +0200
Subject: [PATCH] Use std::array for one-dimensional data

---
 ffcx_backends/cpp.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ffcx_backends/cpp.py b/ffcx_backends/cpp.py
index a8a4bf9..12580b1 100644
--- a/ffcx_backends/cpp.py
+++ b/ffcx_backends/cpp.py
@@ -137,6 +137,12 @@ def format_array_decl(self, arr: L.ArrayDecl) -> str:
 
         vals = Formatter.build_initializer_lists(arr.values)
         cstr = "static const " if arr.const else ""
+
+        # use std::array for one dimensional data
+        if len(arr.sizes) == 1:
+            dim = arr.sizes[0]
+            return f"{cstr}std::array<{typename}, {dim}> {symbol} = {vals};\n"
+
         return f"{cstr}{typename} {symbol}{dims} = {vals};\n"
 
     @__call__.register