计算机c语言实验12

实验12 文件程序设计实验目的1）掌握文件的基本概念2）掌握文本文件的打开和关闭操作3）掌握文本文件的顺序读，写方法实验内容1、基础编程题（2）将实数写入文件：从键盘输入若干实数（以特殊数值-1结束），分别写到一个文本文件中。

试编写相应程序。

2.1程序源代码#include <stdio.h>int main(void){int n;FILE *pf = fopen("1.txt", "w+");if (!pf){puts("open file error!");return -1;}while (true){printf("input a num:");scanf("%d", &n);if (n==-1)break;fprintf(pf, "%d ", n);}fclose(pf);puts("ok!");return 0;}2.2运行结果（3）统计成绩：从键盘输入以下10个学生的学号，姓名，以及数学，语文和英语成绩，写到文本文件f3.txt中，再从文件中取出数据，计算每个学生的总成绩和平均分，并将结果显示在屏幕上。

试编写相应程序。

3.1程序源代码#include<stdio.h>#include<stdlib.h>#include<string.h>void test2();int main(){test2();}struct student{long no;char name[20];int math;int chinese;int english;int sum;double ave;};void test2(){struct student student_1;FILE *fp = NULL;char buff[1000]="学号\t姓名\t数学\t语文\t英语\t总成绩\t平均分";int i;fp = fopen("f3.txt", "w+");fputs(buff,fp);fputs("\n",fp);for(i=0;i<10;i++){scanf("%ld %s %d %d %d",&student_1.no,student_,&student_1. math,&student_1.chinese,&student_1.english);student_1.sum=student_1.math+student_1.chinese+student_1.english;student_1.ave=student_1.sum/3;fprintf(fp,"%ld\t%s\t%d\t%d\t%d\t%d\t%1.0lf\n",student_1.no,student_1 .name,student_1.math,student_1.chinese,student_1.english,student_1.su m,student_1.ave);}printf("%s\n",buff);fseek(fp,sizeof(buff),SEEK_SET);for(i=0;i<10;i++){fscanf(fp,"%ld\t%s\t%d\t%d\t%d\t%d\t%1.0lf\n",&student_1.no,student _,&student_1.math,&student_1.chinese,&student_1.english,&stu dent_1.sum,&student_1.ave);printf("%ld\t%s\t%d\t%d\t%d\t%d\t%1.0lf\n",student_1.no,student_1.na me,student_1.math,student_1.chinese,student_1.english,student_1.sum,st udent_1.ave);}fclose(fp);}3.2运行结果2、改错题将文件中的数据求和并写入文本文件尾：文件Int_Data.dat中存放了若干整数，将文件中所有数据相加，并把累加和写入该文件的最后。

2.1程序源代码#include<stdio.h>#include<stdlib.h>int main(void){FILE fp;int n,sum;if((fp=fopen("Int_Data.dat","r"))==NULL){printf("Can't Open File!");exit(0);}while(fscanf(fp,"%d",&n)==EOF)sum=sum+n;fprintf(fp,"%d",sum);fclose(fp);return 0;}2.2运行结果2.3 实验过程将源代码改为：#include<stdio.h>#include<stdlib.h>int main(){FILE *fp;int n,sum = 0;if((fp=fopen("int_data.dat","a+"))==NULL){printf("Can't Open File!");exit(0);}while(fscanf(fp,"%d",&n) != EOF)sum=sum+n;fprintf(fp," %d",sum);fclose(fp);return 0;}运行结果为：3、拓展编程（2）删除文件中的注释：将C语言源程序（hello.c）文件中的所有注释去掉后存入另一个文件（new_hello.c）.试编写相应程序。

2.1程序源代码#include<stdio.h>#include<stdlib.h>#include<string.h>void test4();int main(){test4();}void test4(){FILE *fp = NULL;FILE *fpcp = NULL;char ch;if((fp = fopen("hello.c","r"))==NULL){ printf("文件不存在");exit(0);};fpcp=fopen("new_hello.c","w");while(!feof(fp)){ch=fgetc(fp);if(ch=='/'){if(fgetc(fp)=='*'){while(fgetc(fp)!='/'){continue;}}}else if(ch!=EOF){fputc(ch,fpcp);}}fclose(fp);fclose(fpcp);}2.2运行结果(3)账户余额管理：创建一个随机文件，用来存储银行账户和余额信息，程序要求能够查询某个账户的余额，当客户发生交易额时（正表示存入，负表示取出），并能更新余额。

账户信息包括：账号，账号名和余额3个数据项。

试编写相应程序3.1程序源代码#include <stdio.h>#include<string.h>#include <stdlib.h>long size;struct account{char no[10];char acctname[50];double balance;};FILE *openfile(char *openmode);double userbalance(FILE *fp,char *name);void pay(FILE *fp,char *name,double count);int main(){FILE *fp;int choice;char name[50];double balance;double count;printf("请输入选择类型\n");printf("1.查账户余额\n");printf("2.账户交易\n");printf("退出按exit\n");scanf("%d",&choice);switch(choice){case 1:{printf("输入名字");scanf("%s",name);fp=openfile("r+");balance=userbalance(fp,name);printf("%.2lf",balance);break;}case 2:{printf("输入名字");scanf("%s",name);fp=openfile("r+");printf("输入交易金额");scanf("%lf",&count);pay(fp,name,count);break;}default:exit(0);break;}}FILE *openfile(char *openmode){FILE *fp;if((fp=fopen("accout.dat",openmode))==NULL){ printf("can't open");exit(0);}return fp;}double userbalance(FILE *fp,char *name){struct account user;double balance;fseek(fp,0L,SEEK_SET);while(!feof(fp)){fscanf(fp,"%s %s %lf",user.no,user.acctname,&user.balance);if(strcmp(user.acctname, name) == 0){balance=user.balance;break;}}return balance;}void pay(FILE *fp,char *name,double count){FILE *fpout;struct account user;double balance;balance=userbalance(fp,name);balance=balance+count;fseek(fp,0L,SEEK_SET);fpout=fopen("temp.dat","w");while(!feof(fp)){fscanf(fp,"%s %s %lf",user.no,user.acctname,&user.balance);if(strcmp(user.acctname, name) == 0){user.balance=balance;//printf("%s %s %lf",user.no,user.acctname,user.balance);fprintf(fpout,"%s %s %lf\n",user.no,user.acctname,user.balance);}else{fprintf(fpout,"%s %s %lf\n",user.no,user.acctname,user.balance);}}fclose(fp);fclose(fpout);unlink("accout.dat");rename("temp.dat","accout.dat");}3.2运行结果实验心得与小结指导教师评议成绩评定：指导教师签名：。