Programming with functions and structures using C, getting strange output, no errors

I'm learning a bit C and i'm doing an e开发者_如何转开发xercise where i use structures and functions to collect employee infos and just print them out. I'm declaring the functions and the struct in the header since i need them in both of the other files.

//employee.h

int addEmployee(void);
int printEmployee(int i);

struct employeelist 
{
    char last [20];
    char first[20];
    int pnumber;
    int salary;
};

The "core" file is executing the both functions. The first function asks for the number of employees and gives a value back for the second function where the information is collected and stored. There are no errors and i've checked the code several times.

//employee.c

#include "employee.h"
#include <stdio.h>
#include <ctype.h>
#include <string.h>

int numE;
int i;

int addEmployee(void)
{
    struct employeelist employee[5]; 
    int numE; 


    printf("How many employees do you want to add to the list?: ");
    scanf("%d", &numE);
    printf("Please type in the last name, the first name,\nthe personal number and the salary of your employees.\n");

    for (i=0; i < numE; i++)
    {

    printf("Last name: ");
    scanf("%s", employee[i].last);  

    printf("First name: ");
    scanf("%s", employee[i].first);  

    printf("Personal number: ");
    scanf("%d", &employee[i].pnumber);  

    printf("Salary: ");
    scanf("%d", &employee[i].salary);  
    }

    return numE;
}

int printEmployee(int emp)
{
    struct employeelist employee[5]; 
    for (i=0; i < emp; i++)
    {

        printf("Last name: {%s}\nFirst name: {%s}\nPersonal number: {%d}\nSalary: {%d}\n",employee[i].last,employee[i].first, employee[i].pnumber, employee[i].salary);
    }

    getchar();
    getchar();
    return emp;
}

The last file contains the main() function to execute the functions above.

#include "employee.h"
#include <stdio.h>
#include <ctype.h>
#include <string.h>

int emp;

int main ()
{
    struct employeelist employee[5]; 
    int emp = addEmployee();
    printEmployee(emp);
    return 0;
}

Now my problem is that everything works only the output is incorrect. I can't even say what it is. Some kind of random mix of signs, letters and numbers. Since i have no idea where my mistake is, i would be glad about any advise to solve this problem. Thank you.

I have added a screenshot of my output. Maybe it helps.

You're trying to use a local variable, which ceases to exist when the function returns.

int addEmployee(void)
{
    struct employeelist employee[5];
    /* ... */
}

The variable employee only exists inside the addEmployee() function; and it is a different object every time the function is called.

int printEmployee(int emp)
{
    struct employeelist employee[5];
    /* ... */
}

This employee has no relation to the one in addEmployee.

But don't do the easy thing now (*); do the right thing: declare the array in the main() function and pass it around.

//employee.h

struct employeelist 
{
    char last [20];
    char first[20];
    int pnumber;
    int salary;
};

/* add up to `maxemp` employees to the array and
** return  number of employees added */
int addEmployee(struct employeelist *, int maxemp);

/* print all employees from index 0 to (nemp - 1) */
int printEmployee(struct employeelist *, int nemp);

Declare an array in main(), and pass it around

#include "employee.h"
#include <stdio.h>
#include <ctype.h>
#include <string.h>

int main ()
{
    int emp;

    struct employeelist employee[5]; 
    int emp = addEmployee(employee, 5);
    printEmployee(employee, emp);
    return 0;
}

_{(*) Don't declare a global variable for employees}

Edited employee.h and added a main() function

You have a brand new variable in your print function that isn't even initialized. So it contains only garbage and that is printed

The heart of the problem is that you're working with three different arrays of employees instead of the one array that you think you've got. Anything declared within a pair of curly braces in C only 'exists' while the program is executing code inside those braces. You've declared three different arrays of employee structs in three different blocks of code.

To point you in the right direction (irrespective of whether this is homework or self-study, this is a learning exercise so just fixing your code probably isn't what you want) you should think about how you can pass the same employee array to each of your functions in turn. (EDIT: pmg beat me to it.)

Declare the array once, in your main() function as you've already done, and modify your two functions printEmployee() and addEmployee() to take that array as a parameter instead of declaring their own local arrays.

Here is a very simple example using ints showing how parameters and return values work. You'll have to do some reading about pointers to extend this to your case.

int main() {
    int number = 2;
    int newNumber;
    newNumber = timesTwo(number);
    printf("number: %d newNumber: %d", number, newNumber);
}

int timesTwo(int param) {
    return param * 2;
}

Before you start breaking things out into separate files and working with structs and pointers it is a good idea to practice the concepts of functions, parameters and variables by building simple programs in a single file.

You declare the employee array locally to both functions, so they cannot access each other's data.

The main issue, as others have already said, is that you are declaring a struct employeelist employee[5] in each of your functions. This makes those variables local to their functions and thus inaccessable from one function to the other. So, when printEmployee goes to print, the data it is printing is gibberish.

There are a few things needed to fix this:

• Make one declaration of your employee list in your main (which you already have) and then pass that into the functions. You'll need to do the passing by means of the array name so that the functions will treat the array properly.
• As a result of the above, you'll need to move the struct declaration to be above the function prototypes and then change the prototypes in employee.h to accomodate the passing of the employeelist.
• You'll have to check that the user doesn't try to enter more records than your array has space for. Alternatively, you could just declare a pointer in the main and malloc() the needed memory in the addEmployee function.

A few other suggestions to make things a little easier on yourself:

• Call your struct employee (or something like that) and your array employeelist (or something similar).
• Use typedef on your struct to shorten & simplify your declarations.
• Change your printEmployee to be a void function (i.e. void return type).

Take a look.. Well distribued and simple to read, it just needs a little improvement to become bigger and do the work u want.

typedef struct
{
  char last [20];
  char first[20];
  long int pnumber;
  int salary;
}employee;

  /* the two functions clearly declared */
  int addEmployee(employee const wEmployeeList[]);
  void printEmployee( employee const wEmployeeList[], int );

int main()
{
   int numberE;
   employee employeeList[2];
   numberE = addEmployee(employeeList);
   printEmployee(employeeList, numberE);

   return 0;
}
int addEmployee(employee const wEmployeeList[2]){

int i;
 for (i=0; i < 2; i++)
{

printf("Last name: ");
scanf("%s", wEmployeeList[i].last);

printf("First name: ");
scanf("%s", wEmployeeList[i].first);

printf("Personal number: ");
scanf("%ld", &wEmployeeList[i].pnumber);

printf("Salary: ");
scanf("%d", &wEmployeeList[i].salary);
}

return 2;
}


void printEmployee(employee const wEmployeeList[2], int numberEmployee){

int i;

for (i=0; i < numberEmployee; i++)
{

    printf("\n\nLast name: %s\nFirst name: %s\nPersonal number: {%ld}\nSalary: {%d}\n     \n",wEmployeeList[i].last,wEmployeeList[i].first, wEmployeeList[i].pnumber,    wEmployeeList[i].salary);
}


}