#include<stdio.h>

main()
{
      	char key;
	FILE *stream;                          /*流的指針*/

	printf("Please input a letter.\n");
	key=getchar();                        /*讀入一個字符*/

	if (stream =fopen("test","r")==(FILE*)0)   /*將流與一個文件聯系起來,
	并判斷是否成功*/
	{
              	fprintf(stderr,"Error opening file.\n");
    		exit(1);
	}

/*將緩沖區設定為行緩沖,并判斷是否成功*/
	if(setlinebuf(stream))!=0)
	{
		fprintf (stderr,"Error setlinebuffer .\n");
		exit(1);
      	}

/*將對應的緩沖區清空,并判斷操作是否成功*/
        if(fpurge(stream))==EOF)
        {
		fprintf(stderr,"Error flush stream.\n");
		exit(1);
      	}

/*對流的讀寫操作*/
	fprintf(stream,"The letter that you input is %c.\n",key);

/*在程序結束前關閉流,并判斷操作是否成功*/
	if(fclose(stream))==EOF)
	{
             	fprintf(stderr,"Error closing file,\n");
     		exit(1);
	}
	exit(0);
}