Fix passing strings from C# to C. (#1701)

See also
https://github.com/k2-fsa/sherpa-onnx/issues/1695#issuecomment-2585725190

We need to place a 0 at the end of the buffer.

@@ -26,7 +26,10 @@ namespace SherpaOnnx
         public OnlineStream CreateStream(string keywords)
         public OnlineStream CreateStream(string keywords)
         {
         {
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(keywords);
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(keywords);
-            IntPtr p = SherpaOnnxCreateKeywordStreamWithKeywords(_handle.Handle, utf8Bytes);
+            byte[] utf8BytesWithNull = new byte[utf8Bytes.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Bytes, utf8BytesWithNull, utf8Bytes.Length);
+            utf8BytesWithNull[utf8Bytes.Length] = 0; // Null terminator
+            IntPtr p = SherpaOnnxCreateKeywordStreamWithKeywords(_handle.Handle, utf8BytesWithNull);
             return new OnlineStream(p);
             return new OnlineStream(p);
         }
         }
 
 

@@ -17,8 +17,11 @@ namespace SherpaOnnx
         public String AddPunct(String text)
         public String AddPunct(String text)
         {
         {
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(text);
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(text);
+            byte[] utf8BytesWithNull = new byte[utf8Bytes.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Bytes, utf8BytesWithNull, utf8Bytes.Length);
+            utf8BytesWithNull[utf8Bytes.Length] = 0; // Null terminator
 
 
-            IntPtr p = SherpaOfflinePunctuationAddPunct(_handle.Handle, utf8Bytes);
+            IntPtr p = SherpaOfflinePunctuationAddPunct(_handle.Handle, utf8BytesWithNull);
 
 
             string s = "";
             string s = "";
             int length = 0;
             int length = 0;

@@ -19,14 +19,20 @@ namespace SherpaOnnx
         public OfflineTtsGeneratedAudio Generate(String text, float speed, int speakerId)
         public OfflineTtsGeneratedAudio Generate(String text, float speed, int speakerId)
         {
         {
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(text);
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(text);
-            IntPtr p = SherpaOnnxOfflineTtsGenerate(_handle.Handle, utf8Bytes, speakerId, speed);
+            byte[] utf8BytesWithNull = new byte[utf8Bytes.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Bytes, utf8BytesWithNull, utf8Bytes.Length);
+            utf8BytesWithNull[utf8Bytes.Length] = 0; // Null terminator
+            IntPtr p = SherpaOnnxOfflineTtsGenerate(_handle.Handle, utf8BytesWithNull, speakerId, speed);
             return new OfflineTtsGeneratedAudio(p);
             return new OfflineTtsGeneratedAudio(p);
         }
         }
 
 
         public OfflineTtsGeneratedAudio GenerateWithCallback(String text, float speed, int speakerId, OfflineTtsCallback callback)
         public OfflineTtsGeneratedAudio GenerateWithCallback(String text, float speed, int speakerId, OfflineTtsCallback callback)
         {
         {
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(text);
             byte[] utf8Bytes = Encoding.UTF8.GetBytes(text);
-            IntPtr p = SherpaOnnxOfflineTtsGenerateWithCallback(_handle.Handle, utf8Bytes, speakerId, speed, callback);
+            byte[] utf8BytesWithNull = new byte[utf8Bytes.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Bytes, utf8BytesWithNull, utf8Bytes.Length);
+            utf8BytesWithNull[utf8Bytes.Length] = 0; // Null terminator
+            IntPtr p = SherpaOnnxOfflineTtsGenerateWithCallback(_handle.Handle, utf8BytesWithNull, speakerId, speed, callback);
             return new OfflineTtsGeneratedAudio(p);
             return new OfflineTtsGeneratedAudio(p);
         }
         }
 
 

@@ -16,7 +16,10 @@ namespace SherpaOnnx
         {
         {
             Impl impl = (Impl)Marshal.PtrToStructure(Handle, typeof(Impl));
             Impl impl = (Impl)Marshal.PtrToStructure(Handle, typeof(Impl));
             byte[] utf8Filename = Encoding.UTF8.GetBytes(filename);
             byte[] utf8Filename = Encoding.UTF8.GetBytes(filename);
-            int status = SherpaOnnxWriteWave(impl.Samples, impl.NumSamples, impl.SampleRate, utf8Filename);
+            byte[] utf8FilenameWithNull = new byte[utf8Filename.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Filename, utf8FilenameWithNull, utf8Filename.Length);
+            utf8FilenameWithNull[utf8Filename.Length] = 0; // Null terminator
+            int status = SherpaOnnxWriteWave(impl.Samples, impl.NumSamples, impl.SampleRate, utf8FilenameWithNull);
             return status == 1;
             return status == 1;
         }
         }
 
 

@@ -18,7 +18,10 @@ namespace SherpaOnnx
         public bool Add(string name, float[] v)
         public bool Add(string name, float[] v)
         {
         {
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
-            return SherpaOnnxSpeakerEmbeddingManagerAdd(_handle.Handle, utf8Name, v) == 1;
+            byte[] utf8NameWithNull = new byte[utf8Name.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Name, utf8NameWithNull, utf8Name.Length);
+            utf8NameWithNull[utf8Name.Length] = 0; // Null terminator
+            return SherpaOnnxSpeakerEmbeddingManagerAdd(_handle.Handle, utf8NameWithNull, v) == 1;
         }
         }
 
 
         public bool Add(string name, ICollection<float[]> v_list)
         public bool Add(string name, ICollection<float[]> v_list)
@@ -33,13 +36,19 @@ namespace SherpaOnnx
             }
             }
 
 
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
-            return SherpaOnnxSpeakerEmbeddingManagerAddListFlattened(_handle.Handle, utf8Name, v, n) == 1;
+            byte[] utf8NameWithNull = new byte[utf8Name.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Name, utf8NameWithNull, utf8Name.Length);
+            utf8NameWithNull[utf8Name.Length] = 0; // Null terminator
+            return SherpaOnnxSpeakerEmbeddingManagerAddListFlattened(_handle.Handle, utf8NameWithNull, v, n) == 1;
         }
         }
 
 
         public bool Remove(string name)
         public bool Remove(string name)
         {
         {
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
-            return SherpaOnnxSpeakerEmbeddingManagerRemove(_handle.Handle, utf8Name) == 1;
+            byte[] utf8NameWithNull = new byte[utf8Name.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Name, utf8NameWithNull, utf8Name.Length);
+            utf8NameWithNull[utf8Name.Length] = 0; // Null terminator
+            return SherpaOnnxSpeakerEmbeddingManagerRemove(_handle.Handle, utf8NameWithNull) == 1;
         }
         }
 
 
         public string Search(float[] v, float threshold)
         public string Search(float[] v, float threshold)
@@ -77,13 +86,19 @@ namespace SherpaOnnx
         public bool Verify(string name, float[] v, float threshold)
         public bool Verify(string name, float[] v, float threshold)
         {
         {
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
-            return SherpaOnnxSpeakerEmbeddingManagerVerify(_handle.Handle, utf8Name, v, threshold) == 1;
+            byte[] utf8NameWithNull = new byte[utf8Name.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Name, utf8NameWithNull, utf8Name.Length);
+            utf8NameWithNull[utf8Name.Length] = 0; // Null terminator
+            return SherpaOnnxSpeakerEmbeddingManagerVerify(_handle.Handle, utf8NameWithNull, v, threshold) == 1;
         }
         }
 
 
         public bool Contains(string name)
         public bool Contains(string name)
         {
         {
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
             byte[] utf8Name = Encoding.UTF8.GetBytes(name);
-            return SherpaOnnxSpeakerEmbeddingManagerContains(_handle.Handle, utf8Name) == 1;
+            byte[] utf8NameWithNull = new byte[utf8Name.Length + 1]; // +1 for null terminator
+            Array.Copy(utf8Name, utf8NameWithNull, utf8Name.Length);
+            utf8NameWithNull[utf8Name.Length] = 0; // Null terminator
+            return SherpaOnnxSpeakerEmbeddingManagerContains(_handle.Handle, utf8NameWithNull) == 1;
         }
         }
 
 
         public string[] GetAllSpeakers()
         public string[] GetAllSpeakers()