【C语言及程序设计】项目2-15：模块化的简单银行系统设计

问题描述：

https://edu.csdn.net/course/play/456/4808

// 银行系统.cpp: 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <stdlib.h>
#pragma warning (disable: 4996)

int  PassTest();
void ibalance();
void withdraw();
void deposit();
void PassChange();

int main()
{
	int ichoice,testresult;

	printf("欢迎光临草泥马银行\n\n");
	testresult = PassTest();

	while (testresult)
	{
		printf("\n您可办理下面的业务：\n");
		printf("   1.查询余额\n");
		printf("   2.取款\n");
		printf("   3.存款\n");
		printf("   4.改密码\n");
		printf("   0.退出\n");
		printf("请输入（0-4）：");

		scanf("%d", &ichoice);

		switch (ichoice)
		{
		case 1:ibalance(); break; 
		case 2:withdraw(); break;
		case 3:deposit(); break;
		case 4:PassChange(); break;
		default:
			break;
		}
		if (ichoice == 0)
		{
			break;
		}
	}
	

    return 0;
}


int PassTest()
{
	printf("请输入6位密码：");
	

	while (1)
	{
		int pass, passstored, itry(1), righttime(0);

		FILE *fp;
		fp = fopen("D:\\code\\pass.dat", "r");
		if (fp == NULL)
		{
			printf("File cannot open! ");
			exit(0);
		}

		for (int i = 0; i < 6; i++)
		{
			scanf_s("%1d", &pass);
			fscanf(fp, "%1d", &passstored);
			if (pass == passstored)
			{
				righttime++;
			}
		}
		
		if (righttime == 6)
		{
			fclose(fp);
			return 1;
			break;
		}
		else if (itry<3)
		{
			itry++;
			printf("密码错误累计%d次，请重新输入：", itry - 1);
			continue;
		}
		else
		{
			printf("密码错误累计%d次，系统终止\n", itry);
			fclose(fp);
			return 0;
			break;
		}
	}
	
}


void ibalance() 
{
	double balance;

	FILE *fp;
	fp = fopen("D:\\code\\balance.dat", "r");
	if (fp == NULL)
	{
		printf("File cannot open! ");
		exit(0);
	}

	fscanf(fp, "%lf", &balance);
	printf("余额：%.2lf\n\n", balance);
	fclose(fp);

}

void withdraw() 
{
	double cash, balance, diff;
	printf("请输入取款额：");
	scanf("%lf", &cash);

	FILE *fp;
	fp = fopen("D:\\code\\balance.dat", "r");
	if (fp == NULL)
	{
		printf("File cannot open! ");
		exit(0);
	}

	fscanf(fp, "%lf", &balance);
	if (balance>cash)
	{
		diff = balance - cash;
		fclose(fp);

		fp = fopen("D:\\code\\balance.dat", "w");
		fprintf(fp, "%lf", diff);

		fclose(fp);

		fp = fopen("D:\\code\\balance.dat", "r");
		fscanf(fp, "%lf", &balance);
		printf("现余额：%.2lf\n\n", balance);
		fclose(fp);
	}
	else
	{
		printf("取款额大于余额，取款失败\n\n");
		fclose(fp);
	}

}


void deposit() 
{
	double cash, balance, diff;
	printf("请输入存款额：");
	scanf("%lf", &cash);

	FILE *fp;


	fp = fopen("D:\\code\\balance.dat", "r");
	if (fp == NULL)
	{
		printf("File cannot open! ");
		exit(0);
	}

	fscanf(fp, "%lf", &balance);
	diff = balance + cash;

	fclose(fp);


	fp = fopen("D:\\code\\balance.dat", "w");
	if (fp == NULL)
	{
		printf("File cannot open! ");
		exit(0);
	}

	fprintf(fp, "%lf", diff);

	fclose(fp);
	

	fp = fopen("D:\\code\\balance.dat", "r");
	if (fp == NULL)
	{
		printf("File cannot open! ");
		exit(0);
	}

	fscanf(fp, "%lf", &balance);
	printf("现余额：%.2lf\n", balance);

	fclose(fp);

}


void PassChange()
{
	while (1)
	{
		int pass, pass2;
		printf("请输入新密码：");
		scanf("%d", &pass);

		if (pass>=100000 && pass <=999999)
		{
			printf("请再输入新密码：");
			scanf("%d", &pass2);

			if (pass == pass2)
			{
				FILE *fp;
				fp = fopen("D:\\code\\pass.dat", "w");

				fprintf(fp, "%d", pass);

				fclose(fp);

				printf("密码修改成功\n");
			}
			break;
		}

		else
		{
			printf("密码位数不足，请输满6位\n");
			continue;
		}
		
	}
	
}

　　

感想：

数据写入硬盘（如写入文本文档）似乎是在fclose之后才生效

比如取款后显示“现余额”，必须这么写

		fp = fopen("D:\\code\\balance.dat", "w");
		fprintf(fp, "%lf", diff);
		fclose(fp);

		fp = fopen("D:\\code\\balance.dat", "r");
		fscanf(fp, "%lf", &balance);
		printf("现余额：%.2lf\n\n", balance);
		fclose(fp);

　　

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