C 为银行记录创建数据库
这是我正在从事的项目的代码,我的目标是创建一个可以添加、编辑和删除记录的数据库。程序正在编译,但速度非常慢,经常崩溃。我只是一个初学者,我不明白为什么会发生这种情况。也许有人能帮我改进代码或者给我指出正确的方向C 为银行记录创建数据库,c,database,C,Database,这是我正在从事的项目的代码,我的目标是创建一个可以添加、编辑和删除记录的数据库。程序正在编译,但速度非常慢,经常崩溃。我只是一个初学者,我不明白为什么会发生这种情况。也许有人能帮我改进代码或者给我指出正确的方向 enter code here #include <stdio.h> #include <stdlib.h> #include <string.h> #include <ctype.h> void clearInput(void); vo
enter code here
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
void clearInput(void);
void listAll (void);
void deleteAccount(void);
void addNewAccount(void);
void modifyAccount(void);
int prompt(void);
struct account{
int number;
char lastname[15];
char firstname[15];
float balance;
struct account*next;
};
struct account *firsta, *currenta, *newa;
int anum = 0;
int main()
{
FILE *datafile;
char *filename="studentdatabase.txt";
char ch;
firsta=NULL;
datafile=fopen(filename, "r");
if (datafile) /*assume doesnt exist otherwise*/
{
firsta=(struct account*)malloc(sizeof(struct account));
currenta=firsta;
while (1)
{
newa=(struct account*)malloc(sizeof(struct account));
fread(currenta, sizeof(struct account),1,datafile);
if (currenta->next==NULL)
break;
currenta->next=newa;
}
fclose(datafile);
anum=currenta->number;
}
do
{
clearInput();
puts("\nA - Add a new account");
puts("D - Delete account");
puts("L - List all accounts");
puts("M - Modify account");
puts("Q - Quit this program\n");
printf("\tYour Choice:");
ch=getchar();
ch=toupper(ch);
switch(ch)
{
case 'A':
puts("Add new account\n");
clearInput();
addNewAccount();
break;
case 'D':
puts("Delete account\n");
deleteAccount();
break;
case 'L':
puts("List all accounts\n");
listAll();
break;
case 'M':
puts("Modify an account\n");
modifyAccount();
break;
case 'Q':
puts ("Quit\n");
default:
break;
}
}
while(ch!='Q');
/*Save the records to disc*/
currenta=firsta;
if(currenta==NULL)
return(0); /*No data to write - End of Program*/
datafile=fopen(filename,"w");
if (datafile=NULL)
{
printf("Error writing to %s\n", filename);
return(1);
}
/*write each record to disc*/
while(currenta!=NULL)
{
fwrite(currenta, sizeof(struct account),1,datafile);
currenta=currenta->next;
}
fclose(datafile);
return(0);
}
/*This function clears any text from the input stream*/
void clearInput(void)
{
fflush(stdin);
}
void addNewAccount(void)
{
newa=(struct account*)malloc(sizeof(struct account));
/*Check to see if this is the first record, if so then
itialize all the pointers to this, first ftrusture in
the database*/
if(firsta==NULL)
firsta=currenta=newa;
/*Otherwise you must find the end of the structure list
(easily spotted by the NULL pointer) and add on the new
structure you just allocated memory for*/
else
{
currenta=firsta; /*makes the first current*/
/*loop throught all records*/
while(currenta->next!=NULL)
currenta=currenta->next;
/*last record found*/
currenta->next=newa; /*save the address of new*/
currenta=newa; /*makes current new*/
}
/*now you just fill in the new structure*/
anum++;
printf("%27s:%5i\n","Account number", anum);
currenta->number=anum;
printf("%27s:","Enter customer's lastname");
gets(currenta->lastname);
printf("%27s:","Enter firstname");
gets(currenta->firstname);
printf("%27f:€","Enter account balance");
scanf("%f", ¤ta->balance);
/*Finally cap the new record with a NULL pointer so
that you know its the last record*/
currenta->next=NULL;
}
void listAll(void)
{
if (firsta==NULL)
puts("There are no records to print out");
else
{
printf("%6s %-15s %-15s €%8.2f\n",
currenta->number,
currenta->lastname,
currenta->firstname,
currenta->balance);
}
while ((currenta=currenta->next) !=NULL);
}
void deleteAccount(void)
{
int record;
struct account *previousa;
if(firsta==NULL)
{
puts("There are no records to delete");
return;
}
listAll();
/*Shows all record first*/
printf("Enter account number to delete: ");
scanf("%d",&record);
currenta=firsta;
while(currenta!=NULL)
{
{
if(currenta->number==record)
{
if(currenta==firsta) /*special condition*/
firsta=currenta->next;
else
previousa->next=currenta->next;
free(currenta);
printf("Account %d deleted! \n", -record);
return;
}
previousa=currenta;
currenta=currenta->next;
}
}
printf("Account %d was not found!\n", record);
puts("Nothing deleted.");
}
void modifyAccount(void)
{
int record;
if (firsta==NULL)
{
puts("There are no records to modify!");
return;
}
listAll(); /*Show all records first*/
printf("Enter account number to modify or change: ");
scanf("%d",&record);
currenta=firsta;
while (currenta!=NULL)
{
if(currenta->number==record)
{
printf("Account €%d:\n", currenta->number);
printf("Last name: %s\n", currenta->lastname);
if (prompt())
gets (currenta->lastname);
printf("firstname %s \n", currenta->firstname);
if (prompt())
gets(currenta->firstname);
printf("Balance %8.2f\n", currenta->balance);
if (prompt())
scanf("%f", ¤ta->balance);
return;
}
else
{
currenta=currenta->next;
}
}
printf("Account %d was not found!\n", record);
}
int prompt(void)
{
char ch;
clearInput();
printf("Update?");
ch=getchar();
ch=toupper(ch);
clearInput();
if(ch=='Y')
{
printf("Enter new. ");
return(1);
}
else return(0);
}
在此处输入代码
#包括
#包括
#包括
#包括
void clearInput(void);
作废列表全部(作废);
作废账户(作废);
作废新增账户(作废);
作废修改账户(作废);
int提示符(void);
结构帐户{
整数;
char lastname[15];
charfirstname[15];
浮动天平;
结构帐户*下一步;
};
结构帐户*firsta、*currenta、*newa;
int-anum=0;
int main()
{
文件*数据文件;
char*filename=“studentdatabase.txt”;
char ch;
firsta=NULL;
数据文件=fopen(文件名,“r”);
如果(数据文件)/*则假定不存在,否则*/
{
firsta=(结构帐户*)malloc(结构帐户大小);
电流A=firsta;
而(1)
{
newa=(结构帐户*)malloc(sizeof(结构帐户));
fread(currenta,sizeof(结构帐户),1,数据文件);
如果(currenta->next==NULL)
打破
currenta->next=newa;
}
fclose(数据文件);
anum=当前A->编号;
}
做
{
clearInput();
放置(“\nA-添加新帐户”);
看跌期权(“D-删除账户”);
看跌期权(“L-列出所有账户”);
看跌期权(“M-修改账户”);
puts(“Q-退出此程序\n”);
printf(“\t您的选择:”);
ch=getchar();
ch=toupper(ch);
开关(ch)
{
案例“A”:
出售(“添加新帐户”);
clearInput();
addNewAccount();
打破
案例“D”:
出售(“删除帐户”);
deleteCount();
打破
案例“L”:
放置(“列出所有帐户”\n);
listAll();
打破
案例“M”:
放置(“修改帐户\n”);
修改账户();
打破
案例‘Q’:
卖出(“退出”);
违约:
打破
}
}
while(ch!=“Q”);
/*将记录保存到光盘*/
电流A=firsta;
如果(currenta==NULL)
返回(0);/*没有要写入的数据-程序结束*/
数据文件=fopen(文件名,“w”);
如果(数据文件=NULL)
{
printf(“写入%s\n”文件名时出错);
申报表(1);
}
/*将每条记录写入光盘*/
while(currenta!=NULL)
{
fwrite(currenta,sizeof(结构帐户),1,数据文件);
currenta=currenta->next;
}
fclose(数据文件);
返回(0);
}
/*此函数用于清除输入流中的任何文本*/
void clearInput(void)
{
fflush(stdin);
}
void addNewAccount(void)
{
newa=(结构帐户*)malloc(sizeof(结构帐户));
/*检查这是否是第一条记录,如果是,则
初始化所有指向此的指针,第一次刷新
数据库*/
if(firsta==NULL)
firsta=当前A=新A;
/*否则,必须找到结构列表的末尾
(很容易被空指针发现)并添加新的
您刚才为其分配内存的结构*/
其他的
{
currenta=firsta;/*产生第一个电流*/
/*循环浏览所有记录*/
while(currenta->next!=NULL)
currenta=currenta->next;
/*最后发现的记录*/
currenta->next=newa;/*保存新地址*/
currenta=newa;/*使当前为新*/
}
/*现在您只需填写新结构*/
anum++;
printf(“%27s:%5i\n”,“账号”,anum);
currenta->number=anum;
printf(“%27s:”,“输入客户的姓氏”);
获取(currenta->lastname);
printf(“%27s:”,“输入名字”);
获取(currenta->firstname);
printf(“%27f:欧元”,“输入账户余额”);
scanf(“%f”,¤ta->balance);
/*最后,用空指针覆盖新记录,以便
你知道这是最后一张唱片吗*/
currenta->next=NULL;
}
void listAll(void)
{
if(firsta==NULL)
看跌期权(“没有可打印的记录”);
其他的
{
printf(“%6s%-15s%-15s€%8.2f\n”,
当前A->编号,
currenta->lastname,
currenta->firstname,
电流A->平衡);
}
while((currenta=currenta->next)!=NULL);
}
作废删除账户(作废)
{
int记录;
printf("%6s %-15s %-15s €%8.2f\n",
currenta->number,...
printf(...);
while ((currenta=currenta->next) !=NULL);
while (currenta != NULL) {
printf(...);
currenta = currenta->next;
}
while (1)
{
newa=(struct account*)malloc(sizeof(struct account));
fread(currenta, sizeof(struct account),1,datafile);
if (currenta->next==NULL)
break;
currenta->next=newa;
}
fread(currenta, sizeof(struct account),1,datafile);
datafile=fopen(filename,"w");
if (datafile=NULL)
^^^