From d0436b9a7b9af2c8c521d6a786376ecce6304275 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 27 Mar 2026 01:38:37 +0000
Subject: [PATCH] Print stdin hint when running interactively without -i
 argument (fixes #1054)

Agent-Logs-Url: https://github.com/BYVoid/OpenCC/sessions/c78e8d52-668f-4683-9439-af68780be669

Co-authored-by: frankslin <748873+frankslin@users.noreply.github.com>
---
 src/tools/CommandLine.cpp | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/tools/CommandLine.cpp b/src/tools/CommandLine.cpp
index f0d5f69b2..bfbd64b03 100644
--- a/src/tools/CommandLine.cpp
+++ b/src/tools/CommandLine.cpp
@@ -18,6 +18,12 @@
 
 #include <fstream>
 
+#ifdef _WIN32
+#include <io.h>
+#else
+#include <unistd.h>
+#endif
+
 #include "src/CmdLineOutput.hpp"
 #include "src/Config.hpp"
 #include "src/Converter.hpp"
@@ -45,6 +51,18 @@ FILE* GetOutputStream() {
 }
 
 void ConvertLineByLine() {
+#ifdef _WIN32
+  if (_isatty(_fileno(stdin))) {
+    fprintf(stderr,
+            "Reading from standard input. Press Ctrl+Z then Enter to "
+            "finish.\n");
+  }
+#else
+  if (isatty(fileno(stdin))) {
+    fprintf(stderr,
+            "Reading from standard input. Press Ctrl+D to finish.\n");
+  }
+#endif
   std::istream& inputStream = std::cin;
   FILE* fout = GetOutputStream();
   bool isFirstLine = true;