CODEWITHSUNDEEP
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Jorgito Aqui
Jorgito Aqui

Reputation: 13

Delete Record in a File (C Programming)

I'm fairly new to C. At the moment, I'm learning about file management. To further my understanding of files I wanted to create a Employee Database System, where the user can Create, Delete, Update or Retrieve an Employee Record. First I created a struct which contains the employee's variables like ID, first name, last name and pay, then a function which creates the records, but the there is the problem. I know how to search from the file (using the ID number) but I don't know how to delete a particular record.

(I'm so sorry because I accidentally deleted my DeleteFunction so I cannot show that particular function in my code)

So here is my code:

   #include <stdio.h>
   #include <string.h>

   typedef struct employee{
   int id;
   char name[40];
   float pay;
   }EMP;

  void CreateEmployee(struct employee [] );
  void DisplayRecord();

  int main() {
      EMP e[20];
      CreateEmployee(e);
      //return 0;
    DisplayRecord();
    return 0;
}


void CreateEmployee(struct employee x[]){
char choice ='y';
int i=0;

//EMP employee[20];


FILE *fp;
fp = fopen("employee.txt","a");
if (fp==NULL){
    printf("File not created");
}
while((choice == 'Y') || (choice =='y')){
    printf("Enter the employee's id:");
    scanf("%i",&x[i].id);
    fprintf(fp,"%i\t",x[i].id);

    printf("\nEnter the employee's name:");
    scanf("%s",x[i].name);
    fprintf(fp,"%s\t",x[i].name);

    printf("\nEnter the employee's pay:");
    scanf("%f",&x[i].pay);
    fprintf(fp,"%.2f\t\n",x[i].pay);

    printf("\nEnter another employee?\n");
    printf("Y - Yes     N - No:\n");

    scanf("\n%c",&choice);
     i++;
}

fclose(fp);

}

void DisplayRecord(){

EMP temp;

FILE *fp = fopen("employee.txt", "r");

if(fp != NULL)
{

    while( !feof(fp) )
    {
        fscanf(fp, "%i %s  %f", &temp.id, temp.name, &temp.pay);

        printf("%i %s %f\n",temp.id, temp.name, temp.pay);
    }

    fclose(fp);
    }
else
 {
    printf("An error occurred opening the file\n");
 }
}

I don't know how to use random access file as yet; that's why I'm using sequential access at the moment.

Upvotes: 1

Views: 7139

Answers (1)

Roland Illig
Roland Illig

Reputation: 41625

To delete a record, you have several choices:

  1. Prepare by having a deleted field in each record, and when reading records, skip those that have deleted == true. To actually delete a record, set its deleted flag to true and save it.

  2. Read the data file and write all records to a temporary file, except the one you want to delete. Finally, rename the temporary file to employees.txt.

  3. Switch to a real database for managing the records, since all the typical operations are fast and easy then.

By the way, you haven't said why you love C as a programming language. If it is because you can quickly get your things done, you will be disappointed as soon as your programs get a little larger, since you have to do the memory management and error handling explicitly in your code. And, C makes it very easy to shoot you in the foot (so your program crashes and just doesn't work), since it doesn't have built-in memory protection. Therefore, before totally falling in love with that language, look around a little bit too see whether you can find something better.

Upvotes: 2

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