text: #include <stdio.h>
  // stdin  std 标准 输入流
  // stdout 输出流
  // stderr 错误流
  int main()
  {
  	//printf("please input the value a:\n");
  	fprintf(stdout, "please input the value a:\n");
  	//printf("hello world!\n");
  	int a;
  	//scanf("%d", &a);
  	fscanf(stdin,"%d", &a);
  	if(a<0) {
  		fprintf(stderr, "the value must > 0\n");
  		return 1;
  	}
  	//printf("input value is :%d\n", a);
  	return 0;
  }
  
  