c言語ファイル総合:資金口座管理

<span style="font-size:18px;"># include <stdio.h>
# include <stdlib.h>

long size;           /*          */
typedef struct LogData
{
	long logid;   //  ID
	char logdate[11];  //       
	char lognote[15];   //      
	double charge;  //     
	double balance; //  
}	dat;

//      
int inputchoice()
{
	int maychoice;
	printf("
Enter your choice：
");
	printf("1-Add a new cash
2-List All Cash LOG
3-Query Last Cash LOG
0-End program
");
	scanf("%d", &maychoice);
	
	return maychoice;
}
//        
long getLogcount(FILE *cfptr)
{
	long begin, end, logcount;
	fseek(cfptr, 0L, SEEK_SET); // int fseek(FILE * stream,long offset,int whence);
								//	   whence       :
                                //   SEEK_SET      offset          。SEEK_CUR             offset    。
								//	 SEEK_END              offset    。
								//	 whence  SEEK_CUR  SEEK_END ，  offset       
	begin = ftell(cfptr);      //               。  stream         
	fseek(cfptr, size, SEEK_END);
	end = ftell(cfptr);     
	logcount = (end-begin) / size - 1;
	return logcount;
}
//         
void ListAllLog(FILE *cfptr)
{
	dat log;
	fseek(cfptr, 0l, SEEK_SET);
	fread(&log, size, 1, cfptr); //          log:        size:           ，      1:       ，     size    cptr：   
	printf("logid logdate lognote charge balance
");
	while(!feof(cfptr))  //feof       ，    0 ，    0，        clearerr()  
	{
		printf("%6ld%-11s%-15s%10.2lf%10.2lf
", log.logid, log.logdate, log.logdate, log.charge, log.balance);
	}
}
//          
void QueryLastLog(FILE *cfptr)
{
	dat log;
	long logcount;
	logcount = getLogcount(cfptr);
	if (logcount>0)								//       
	{
		fseek(cfptr, size*(logcount-1), SEEK_SET);	//      
		fread(&log, size, 1, cfptr);
		printf("The last log is:
");
		printf("logid-6ld
logdate:%-11s
lognote:%-15s
", log.logid, log.logdate, log.lognote);
		printf("charge:%-10.2lf
balance:%-10.2lf
", log.charge, log.balance);
	}
	else printf("no logs in file
");
}
//     
void AddNewLog(FILE *cfptr)
{
	dat log, lastlog;
	long logcount;
	printf("Input Logdate(format:2006-01-01):");
	scanf("%s", log.logdate);
	printf("Input Lognote:");
	scanf("%s", log.lognote);
	printf("Input charge:income+ and expend -:");
	scanf("%lf", &log.charge);
	logcount = getLogcount(cfptr);

	if (logcount>0)
	{
		fseek(cfptr, size*(logcount-1), SEEK_SET);
		fread(&lastlog, size, 1, cfptr);
		log.logid = lastlog.logid+1;
		log.balance = log.charge + lastlog.balance;
	}
	else
	{
		log.logid = 1;
		log.balance = log.charge;
	}
	rewind(cfptr);
	printf("logid = %ld
", log.logid);
	fwrite(&log, sizeof(dat), 1, cfptr);
}

FILE *openfile(char *openmod)
{
	FILE *fp;
	if ((fp = fopen("cashbox.dat", openmod)) == NULL)
	{
		printf("Cannot Open file
");
		exit(0);
	}
	return (fp);
}

int main(void)
{
	FILE *fp; 
	int choice;
	while((choice=inputchoice()) != 0)
	{
		switch(choice)
		{
		case 1:
			fp = openfile("ab+");
			AddNewLog(fp);
		case 2:
			fp = openfile("rb");
			ListAllLog(fp);
		case 3:
			fp = openfile("rb");
			QueryLastLog(fp);
			break;
		default:
			printf("Input Error");
			break;
		}
	}
	if (fclose(fp))
	{
		printf("Cannot close the fiel!
");
		exit(0);
	}

	return 0;
}</span>