From daaee30be843d3d764f7613c6f72bab5a782ba23 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maximilian=20Ke=C3=9Fler?= <git@maximilian-kessler.de>
Date: Sat, 4 Nov 2023 19:06:12 +0100
Subject: [PATCH] throw error when input file cannot be opened

---
 example.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/example.cpp b/example.cpp
index 07bb12a..62a8292 100644
--- a/example.cpp
+++ b/example.cpp
@@ -13,6 +13,9 @@ int main(int argc, char** argv)
    }
 
    std::fstream input_file_graph{argv[1]};
+   if (not input_file_graph.is_open()) {
+      throw std::runtime_error(std::string("Could not open file for reading: ") + argv[1]);
+   }
    ED::Graph const graph = ED::Graph::read_dimacs(input_file_graph);
 
    ED::Graph greedy_matching_as_graph{graph.num_nodes()};