请写一个c++使用ONNX的demo

下面是一个简单的使用ONNX的C语言程序示例：

#include <onnxruntime_c_api.h>
#include <stdio.h>

int main() {
  OrtEnv* env;
  OrtStatus* status = OrtCreateEnv(ORT_LOGGING_LEVEL_WARNING, "test", &env);

  OrtSessionOptions* session_options;
  status = OrtCreateSessionOptions(&session_options);

  OrtSession* session;
  char* model_path = "your_model.onnx";
  status = OrtCreateSession(env, model_path, session_options, &session);

  OrtAllocator* allocator;
  status = OrtCreateDefaultAllocator(&allocator);

  // input data
  float input_data[1][3] = {{1.0f, 2.0f, 3.0f}};
  OrtValue* input_tensor = NULL;
  status = OrtCreateTensorWithDataAsOrtValue(allocator, input_data, sizeof(float), (int64_t[]) {1, 3}, &input_tensor);

  // output data
  float output_data[1][2];
  OrtValue* output_tensor = NULL;
  status = OrtCreateTensorWithDataAsOrtValue(allocator, output_data, sizeof(float), (int64_t[]) {1, 2}, &output_tensor);

  // run model
  const char* input_names[1] = {"input_1"};
  const char* output_names[1] = {"output_1"};
  status = OrtRun(session, NULL, input_names, (const OrtValue* const*)&input_tensor, 1, output_names, 1, &output_tensor);

  // get output data
  OrtGetTensorMutableData(output_tensor, (void**) &output_data);

  // print result
  printf("Result: %f %f\n", output_data[0][0], output_data[0][1]);

  // release resources
  OrtReleaseValue(input_tensor);
  OrtReleaseValue(output_tensor);
  OrtReleaseSession(session);
  OrtReleaseSessionOptions(session_options);
  OrtReleaseEnv(env);

  return 0;
}

请注意，您需要将模型文件路径替换为您自己的模型文件。