structs...annoying compilation problem

This is a discussion on structs...annoying compilation problem within the C Programming forums, part of the General Programming Boards category; I can't seem to get the following to compile: Code: #include <stdio.h> #include <stdlib.h> #include <string.h> void fillEmployee(employee emp, char ...

  1. #1
    Learner Axel's Avatar
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    structs...annoying compilation problem

    I can't seem to get the following to compile:

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    void fillEmployee(employee emp, char *name, double rate, int num);
    void swap(employee employees[], int a, int b);
    void sortEmployees(employee employees[], int number);
    void printEmployees(employee employees[], int number);
    
    struct employeeRecord
    {
       char surname[20];
       double hourlyRate;
       int empNumber;
    }
    typedef struct employeeRecord employee;
    
    int main()
    {
            employee employees[5];
    
    }

    5: error: syntax error before "emp"
    6: error: syntax error before "employees"
    7: error: syntax error before "employees"
    8: error: syntax error before "employees"


    why is it not accepting employee employees[] as the parameter for the prototype methods

  2. #2
    aoeuhtns
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    The type 'employee' has not been defined, and the compiler reads code from front to end. Put your struct description and typedef before your function declarations. And I think you want a semicolon after your struct description.

  3. #3
    Registered User
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    You need to put the struct def above the functions that use it. Also you can simplify your struct defintion and typedef into a single statement

    Code:
    typedef struct employeeRecord
    {
       char surname[20];
       double hourlyRate;
       int empNumber;
    }employee;
    Doesn't help any preformance wise, but just cleans up the code a bit.

  4. #4
    Learner Axel's Avatar
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    oh i see thanks.

    Hmm another problem has come up:

    Code:
    void fillEmployee(employee emp, char *name, double rate, int num)
    {
       strcpy(emp->surname, name);
      emp->hourlyRate = rate;
      emp->empNumber = num;
    }

    37: error: invalid type argument of `->'
    38: error: invalid type argument of `->'
    39: error: invalid type argument of `->'


    even emp->hourlyRate = 18; doesn't seem to work.

  5. #5
    Just Lurking Dave_Sinkula's Avatar
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    The -> operator is used with a pointer to a struct or union: emp is neither.
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  6. #6
    aoeuhtns
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    The -> operator is used for memory addresses. Dot is used for structures themselves. In the following example, we let x be an employee structure, and we have y be a memory address of an employee structure.

    Code:
    employee x;
    employee *y; /* y can hold a memory address of an employee. */
    int u,v;
    x.empNumber = 7;
    u = x.empNumber; /* assigns 7, the value in x.empNumber, to u */
    
    y = &x; /* Assign to y the memory address of x. */
    u = (*y).empNumber; /* Dereferences y, gets the empNumber member. */
    
    if (u == v) puts("They're both seven!");
    
    u = y->empNumber; /* Dereferences y, gets the empNumber member (like before). */
    if (u == v) puts("Again!");
    
    y->empNumber = 3; /* same as (*y).empNumber = 3 */
    if (x.empNumber == 3) puts ("Three!");
    In C, ((*a).b) means the same thing as (a->b)

  7. #7
    Learner Axel's Avatar
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    thanks.

    Hmm i can't seem to print out the values inside the struct. It just prints out long numbers for some reason:

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    typedef struct employeeRecord employee;
    
    struct employeeRecord
    {
       char surname[20];
       double hourlyRate;
       int empNumber;
    };
    
    void fillEmployee(employee emp, char *name, double rate, int num);
    void swap(employee employees[], int a, int b);
    void sortEmployees(employee employees[], int number);
    void printEmployees(employee employees[], int number);
    
    int main()
    {
       employee employees[5];
    
       fillEmployee(employees[0], "Sandra", 35.75, 053);
        printEmployees(employees, 5);
      return 0;
    }
    
    
    
    void fillEmployee(employee emp, char *name, double rate, int num)
    {
      strcpy(emp.surname, name);
      emp.hourlyRate = rate;
      emp.empNumber = num;
    
    }
    
    void printEmployees(employee employees[], int number)
    {
       int i;
    
       for (i=0; i<number; i++)
       {
       //  printf("%-20s%4d   %.2f\n", employees[i].surname,
         //    employees[i].empNumber, employees[i].hourlyRate);
           printf("\n%d", employees[i].empNumber);
       }
       printf("\n");
    }
    gives me the following:


    0
    0
    -1073743504
    134513333
    1311707124


  8. #8
    aoeuhtns
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    You need to change fillEmployee to accept a pointer to an employee. Otherwise, you're modifying the values of a copy, not the original.

    Also, even if you filled your first employee successfully, you'd still be printing out the contents of four other noninitialised employees.

    By the way, 053 is not fifty-three.

  9. #9
    Learner Axel's Avatar
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    Quote Originally Posted by Rashakil Fol
    You need to change fillEmployee to accept a pointer to an employee.
    hmm where do i get that pointer from?

    is it possibly like this?

    fillEmployee(*employees, "Cogswell", 35.75, 43);

    i tried it and it made no difference.



    Also, even if you filled your first employee successfully, you'd still be printing out the contents of four other noninitialised employees.
    yup, i pull those out on purpose to minimize the code.


    fillEmployee(employees[1], "Alroy", 12.00, 163);
    fillEmployee(employees[2], "Jetson", 15.75, 97);
    fillEmployee(employees[3], "Astro", 10.25, 104);
    fillEmployee(employees[4], "Sprocket", 22.75, 15);

    [/QUOTE]

    By the way, 053 is not fifty-three.
    fixed

  10. #10
    Learner Axel's Avatar
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    Ok, i don't know if this is the ideal way of doing it but what i've done is:

    modified the fillEmployee method, i've included an index parameter (int). In the main method i access the fill method and pass along the index number, name, hourly rate etc.

    The fillEmployee method then uses this to fill the struct:

    employees[number].hourlyRate = rate;
    so if i pass the index 2 then the 2nd struct name will be filled etc.
    ...etc

    which is then printed.

    I'm intrested to know the pointer variation to the solution :-)

  11. #11
    Frequently Quite Prolix dwks's Avatar
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    Code:
    struct employees, *pemp;
    pemp = &employees[number];
    
    // employees[number].hourlyRate == pemp->hourlyRate by now
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


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  12. #12
    Frequently Quite Prolix dwks's Avatar
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    I think, I don't know, that
    Code:
    typedef struct employeeRecord employee;
    
    struct employeeRecord
    {
       char surname[20];
       double hourlyRate;
       int empNumber;
    };
    Should be
    Code:
    struct employeeRecord
    {
       char surname[20];
       double hourlyRate;
       int empNumber;
    };
    
    typedef struct employeeRecord employee;
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


    Other boards: DaniWeb, TPS
    Unofficial Wiki FAQ: cpwiki.sf.net

    My website: http://dwks.theprogrammingsite.com/
    Projects: codeform, xuni, atlantis, nort, etc.

  13. #13
    Just Lurking Dave_Sinkula's Avatar
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    It doesn't need to be. Some prefer doing it the former way.
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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