uld read the information from the file (reversing what writeEmpToFile does), create a new employee and fill in the data. If the F

Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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readEmpFromFile

 

 

Implement a function readEmpFromFile that takes a FILE * as the only argument and returns a pointer to a struct employee. This function should read the information from the file (reversing what writeEmpToFile does), create a new employee and fill in the data. If the FILE has no more info (is at end of file), this function should return NULL. This function must also ensure any employee actually created (not the NULL) is added to the array (as is done in createEmployee).

Change main to load employees from a file using a command called LOAD which is given to the program using (using your readEmpFromFile function you just wrote).

 

void main(void) {

 

  int end = 1;

 

  char * command;

 

  char buff[256];

 

  char * findEmp;

 

  char findBuff[256];

 

  char * sortType;

 

  char sortBuff[256];

 

  char hire[] = "HIRE";

 

  char list[] = "LIST";

 

  char quit[] = "QUIT";

 

  char find[] = "FIND";

 

  char fire[] = "FIRE";

 

  char _sort[] = "SORT";

 

  char salary[] = "SALARY";

 

  char name[] = "NAME";

  char save[] = "SAVE";

 

  printf("Welcome to the Employee Manager dashboard!\n");

 

  while (end) {

 

    printf("Would you like to HIRE, LIST, FIND, FIRE, SORT,SAVE or QUIT?\n\n");

 

    scanf("%s", buff);

 

    command = malloc(strlen(buff + 1));

 

    strcpy(command, buff);

 

    printf("You entered the command: %s\n\n", command);

 

    if (!strcmp(command, hire)) {

 

      createEmployee();

 

    } else if (!strcmp(command, list)) {

 

      listEmployees();

 

    } else if (!strcmp(command, find)) {

 

      printf("Enter an employee name, to find if they are a current employee:\n\n");

 

      scanf("%s", findBuff);

 

      findEmp = malloc(strlen(findBuff + 1));

 

      strcpy(findEmp, findBuff);

 

      findEmployee(findEmp);

 

    } else if (!strcmp(command, fire)) {

 

      printf("Enter an employee name, to fire\n\n");

 

      scanf("%s", findBuff);

 

      findEmp = malloc(strlen(findBuff + 1));

 

      strcpy(findEmp, findBuff);

 

      fireEmployee(findEmp);

 

    } else if (!strcmp(command, _sort)) {

 

      printf("Would you like to sort by SALARY or NAME?\n\n");

 

      scanf("%s", sortBuff);

 

      sortType = malloc(strlen(sortBuff + 1));

 

      strcpy(sortType, sortBuff);

 

      if (!strcmp(sortType, name)) {

 

        printf("sorting by name\n\n");

 

        sort(emps, EMPS_SIZE, nameComp);

 

        listEmployees();

 

      } else if (!strcmp(sortType, salary)) {

 

        printf("sorting by salary\n\n");

 

        sort(emps, EMPS_SIZE, salaryComp);

 

        listEmployees();

 

      } else {

 

        printf("Improper sort type entered, exiting to main menu\n\n");

 

      }

 

    } else if (!strcmp(command, save)) {

 

      printf("Enter file name:\n\n");

      char filename[15];

      scanf("%s", filename);

      FILE *f;

      f = fopen(filename,"wb");  

      writeEmpToFile(emps,f);

    } else if (!strcmp(command, quit)) {

 

      printf("Quitting the managers dashboard!\n\n");

 

      end = 0;

 

    } else {

 

      printf("Please enter a proper command\n\n");

 

    }

 

  }

 

}

void writeEmpToFile(Employee *emp, FILE *f) {

    if(f!=NULL){

    for (int i = 0; i < MAX_EMPS; i++) {

    if (emps[i] != NULL) {

         fwrite(&emps[i]->salary, sizeof(emps[i]->salary), 1, f);

         fwrite(&emps[i]->yearBorn, sizeof(emps[i]->yearBorn), 1, f);

         fwrite(& emps[i]->ssn, sizeof(char), SSN_SIZE, f);

         int len = strlen(emps[i]->name) + 1;

         fwrite(&len, sizeof(int), 1, f);

         fwrite(&emps[i]->name, sizeof(emps[i]->name), len, f);

        }

     }

    printf("Data written succesfully\n");

    fclose(f);

    }

    else{

        printf("Error while opening file\n");

    }

   

}



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