返回：贺老师课程教学链接

1、阅读下面的程序，写出输出结果，并上机运行程序进行对照

#include "stdio.h"
int main()
{FILE *outfile,*infile;outfile=fopen("data.dat","w");fprintf(outfile, "1111111111\n");fprintf(outfile, "aaaaaaaaaa\n");fprintf(outfile,"AAAAAAAAAA\n");fprintf(outfile,"**********\n");fclose(outfile);infile=fopen("data.dat","r");char line[80];int i=0;while(!feof(infile)){i++;fgets(line,sizeof(line), infile);printf("%d: %s", i, line);}fclose(infile);return 0;
}

2、区分ASCII文件和二进制文件：阅读并运行下面的两个程序，分别用记事本和二进制文件阅读器（请自行下载Binary Viewer等程序，或者用DOS中的Debug程序，并百度其用法）。查看其内容，并理解文件存储的原理。
（1）

#include <stdio.h>
#include <stdlib.h>
int main()
{FILE *outfile;int a;outfile=fopen("f1.dat","w");if(!outfile){printf("open error!\n");exit(1);}scanf("%d", &a);fprintf(outfile, "%d", a);fclose(outfile);return 0;
}

（2）

#include <stdio.h>
#include <stdlib.h>
int main()
{FILE *outfile;int a;outfile=fopen("f2.dat","wb");if(!outfile){printf("open error!\n");exit(1);}scanf("%d", &a);fwrite(&a, sizeof(int), 1, outfile);fclose(outfile);return 0;
}

3、阅读下面的程序，指出其功能，体会fseek()等与文件指针相关的函数的功能及其用法
（1）请说出程序的输出

#include <stdio.h>
#include <stdlib.h>
char *filename = "a.txt";
int main()
{FILE *file;long l,m;file=fopen(filename,"rb");if(!file){printf("open error!\n");exit(1);}l = ftell(file);  //ftell函数返回文件位置指针相对于文件首的偏移量fseek(file, 0, SEEK_END);m = ftell(file);fclose(file);printf("size of %s is %ld bytes.\n", filename, (m-l));return 0;
}

（2）请说出运行程序后test.txt中的内容

#include <stdio.h>
#include <stdlib.h>
int main()
{FILE *outfile;long pos;outfile=fopen("test.txt","w");if(!outfile){printf("open error!\n");exit(1);}fwrite ("This is an apple",16, 1, outfile);pos=ftell(outfile);fseek(outfile, pos-7, SEEK_SET);fwrite (" sam", 4, 1, outfile);fclose(outfile);return 0;
}