to write data to a binary file error occurred in c

Ken H

13y1.8k

hi friend,

when I input the employee post memory error occurred.

Please help me, thanks.

Code is as follows:

#include

#define EMP_NUM_MAX 100

struct EmployeeInfo // employee information structure

{

char name[15];

int empID;

float salary;

char post[15];

}emp[EMP_NUM_MAX];

// function prototype declaration

void MainMenu(),void WriteData();

// main function

void main(void)

{

int choice;

MainMenu();

printf("\t\tPlease enter your choice:");

scanf("%d",&choice);

switch (choice)

{

case 1:

WriteData();

break;

}

void MainMenu() // operator menu

{

system("cls"); // clear the screen

printf("\n\t\t **********************************************\n");

printf("\t\t * Employee Salary Management System For V1.0 *\n");

printf("\t\t **********************************************\n\n");

printf("\t\t 1.Add Employee Information\n");

printf("\t\t 2.Display All Employee Information\n");

printf("\t\t 3.Delete Employee Information\n");

printf("\t\t 4.Find Employee Records\n\n");

}

void WriteData()

{

FILE *fp;

int emp_num;

printf("\t\t You want to input the number of employees?:");

scanf("%d",&emp_num);

for(int i=0;i

{

printf("\t\tPlease input employee name:");

scanf("%s",emp[i].name);

printf("\t\tPlease input employee ID:");

scanf("%d",&emp[i].empID);

printf("\t\tPlease input employee salary:");

scanf("%f",&emp[i].salary);

printf("\t\tPlease input employee post:"); // here occurred error

scanf("%s",emp[i].post);

}

if((fp=fopen("EmployeeInfo.dat","ab"))==NULL) // open binary file

{

printf("Can't open file\n");

exit(1);

}

for(int j=0;j

{

if(fwrite(&emp[j],sizeof(struct EmployeeInfo),1,fp)!=1) //writing data to binary file

printf("Error writing file.\n");

}

fclose(fp); // close file point

}

void DeleteEmployeeInfo()

{

int empID;

printf("Please enter the employee's ID to be deleted:");

scanf("%d",&empID);

here i want to delete the employee ID

}

7 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes13y ago
Accepted answer
I'm not sure whether you're compiling this as a C program - in which case there's a page full of compiler errors - or a C++ program in which case there's (effectively) only one which can be fixed by changing this line:

void MainMenu(), void WriteData();

to this:

void MainMenu(), WriteData();

As regards the run-time error, the one I'm getting just before the line you've marked is:

runtime error R6002
- floating point support not loaded

This can be fixed by initializing the float field to (say) zero before calling scanf which forces floating point support to be loaded.

I've also added one or two other lines to improve the format of the display:

#include
#include
#define EMP_NUM_MAX 100

struct EmployeeInfo // employee information structure
{
char name[15];
int empID;
float salary;
char post[15];
}emp[EMP_NUM_MAX];

// function prototype declaration
void MainMenu(), WriteData(); /* removed second void */

// main function
void main(void)
{
int choice;
MainMenu();

printf("\t\tPlease enter your choice:");
scanf("%d",&choice);
printf("\n\n"); /* added this line */
switch (choice)
{
case 1:
WriteData();
break;
}

}

void MainMenu() // operator menu
{
system("cls"); // clear the screen
printf("\n\t\t **********************************************\n");
printf("\t\t * Employee Salary Management System For V1.0 *\n");
printf("\t\t **********************************************\n\n");
printf("\t\t 1.Add Employee Information\n");
printf("\t\t 2.Display All Employee Information\n");
printf("\t\t 3.Delete Employee Information\n");
printf("\t\t 4.Find Employee Records\n\n");
}

void WriteData()
{
FILE *fp;
int emp_num;

printf("\t\t You want to input the number of employees?:");
scanf("%d",&emp_num);
for(int i=0;i
{
printf("\n"); /* added this line */
printf("\t\tPlease input employee name:");
scanf("%s",emp[i].name);
printf("\t\tPlease input employee ID:");
scanf("%d",&emp[i].empID);
printf("\t\tPlease input employee salary:");
emp[i].salary = 0.0f; /* added this line */
scanf("%f",&emp[i].salary);
printf("\t\tPlease input employee post:"); // error gone now
scanf("%s",emp[i].post);
}

if((fp=fopen("EmployeeInfo.dat","ab"))==NULL) // open binary file
{
printf("Can't open file\n");
exit(1);
}
for(int j=0;j
{
if(fwrite(&emp[j],sizeof(struct EmployeeInfo),1,fp)!=1) //writing data to binary file
printf("Error writing file.\n");
}
fclose(fp); // close file point
}

void DeleteEmployeeInfo()
{
int empID;
printf("Please enter the employee's ID to be deleted:");
scanf("%d",&empID);
/*
here i want to delete the employee ID
*/
}
0
Ken H13y ago
hi,
my problem have been solved.thank for Vulpes. :)

Regards.

Ken.
0
Vulpes13y ago
I think what you'll need to do is to read the file again (or perhaps for the first time), check that an employee record with that ID exists and, if it does, overwrite the file by writing all the records back except the one to be deleted:

void DeleteEmployeeInfo()
{
FILE *fp;
int empID;
int todelete = -1;
int i = 0;
printf("Please enter the employee's ID to be deleted:");
scanf("%d",&empID);

/* load or reload the file and check that record with that ID exists */
if((fp=fopen("EmployeeInfo.dat","rb"))==NULL) // open binary file
{
printf("Can't open file\n");
exit(1);
}

do
{
fseek(fp,i*sizeof(struct EmployeeInfo),SEEK_SET); // move file head location
if(fread(&emp[i],sizeof(struct EmployeeInfo),1,fp))
{
if (emp[i].empID == empID) todelete = i;
i++;
}
}while(!feof(fp));
fclose(fp);

if (todelete == -1)
{
printf("A employee with that ID doesn't exist\n");
}
else
{
/* write records back to file excluding one to be deleted */
if((fp=fopen("EmployeeInfo.dat","wb"))==NULL) // open binary file
{
printf("Can't open file\n");
exit(1);
}

for(int j=0;j
{
if (j == todelete) continue; /* skip record to be deleted */
if(fwrite(&emp[j],sizeof(struct EmployeeInfo),1,fp)!=1) //writing data to binary file
printf("Error writing file.\n");
}
fclose(fp); // close file point
}
}
0
Ken H13y ago
i want deletes the specified employee ID information,but currently there is no better algorithm.
void DeleteEmpInfo()
{
FILE *fp;
int empID;
printf("\n\t\tPlease input you want delete employee id:");
scanf("%d",&empID);

}

thanks.
0
Ken H13y ago
hello Vulpes,

thank for your answer.:)

Regards.

ken
0
Vulpes13y ago
On the first point, scanf is best avoided if you want to read anything which includes spaces.

I'd replace:

scanf("%s",emp[i].post);

with these two lines:

getchar();
gets(emp[i].post);

The first of these lines consumes the new line character left in the buffer by the previous scanf call.

On the second point, you need to check the return value of fread to check that it's actually reading some bytes:

do
{
fseek(fp,i*sizeof(struct EmployeeInfo),SEEK_SET); // move file head location
if(fread(&emp[i],sizeof(struct EmployeeInfo),1,fp)) // read data save to structure variable
{
printf("\t\t%5s\t%4d\t%f\t%s\n",emp[i].name,emp[i].empID,emp[i].salary,emp[i].post);
i++;
}

}while(!feof(fp));
0
Ken H13y ago
hello Vulpes,
thank for your answer, and now I have encountered two problems:
1.when i input the "post", if the input is two words, it will eventually save the first word will be truncated after the second, but I have "post" array is set to 20 and it should not happen of error.
2.suppose i just input the two records, and when I choose to display all the employee information,but it outputs the three records.

code is as follows:
void DisplayEmployeeInfo()
{
FILE *fp;
printf("\n\t\t%s\t%s\t%s\t%s\n","EmpName","EmpID","EmpSalary","EmpPost"); // column headings
if((fp=fopen("EmployeeInfo.dat","rb"))==NULL) // open binary file
{
printf("Can't open file\n");
exit(1);
}

int i=0;
do
{
fseek(fp,i*sizeof(struct EmployeeInfo),SEEK_SET); // move file head location
fread(&emp[i],sizeof(struct EmployeeInfo),1,fp); // read data save to structure variable
printf("\t\t%5s\t%4d\t%f\t%s\n",emp[i].name,emp[i].empID,emp[i].salary,emp[i].post);
i++;
}while(!feof(fp));
fclose(fp);
}

**********************************************
* Employee Salary Management System For V1.0 *
**********************************************

1.Add Employee Information
2.Display All Employee Information
3.Delete Employee Information
4.Find Employee Records

Please enter your choice:1
You want to input the number of employees?:2

Please input employee name:jum
Please input employee ID:2013001
Please input employee salary:35000.00
Please input employee post:Management

Please input employee name:ken
Please input employee ID:2013002
Please input employee salary:25000.00
Please input employee post:IT Engineer /*here this two words*/

Please enter your choice:2

EmpName EmpID EmpSalary EmpPost
jum 2013001 35000.000000 Management
ken 2013002 25000.000000 IT /*it should be:IT Engineer*/
0 0.000000

0