1 files changed, 6 insertions, 2 deletions
diff --git a/examples/two-scales.rs b/examples/two-scales.rs
index d45f67a..6e1dfa4 100644
--- a/examples/two-scales.rs
+++ b/examples/two-scales.rs
@@ -1,8 +1,8 @@
 use plotters::prelude::*;
 
+const OUT_FILE_NAME: &'static str = "plotters-doc-data/twoscale.png";
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let root =
-        BitMapBackend::new("plotters-doc-data/twoscale.png", (1024, 768)).into_drawing_area();
+    let root = BitMapBackend::new(OUT_FILE_NAME, (1024, 768)).into_drawing_area();
     root.fill(&WHITE)?;
 
     let mut chart = ChartBuilder::on(&root)
@@ -48,6 +48,10 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         .background_style(&RGBColor(128, 128, 128))
         .draw()?;
 
+    // To avoid the IO failure being ignored silently, we manually call the present function
+    root.present().expect("Unable to write result to file, please make sure 'plotters-doc-data' dir exists under current dir");
+    println!("Result has been saved to {}", OUT_FILE_NAME);
+
     Ok(())
 }
 #[test]