C collections and pointers error - assignment from incompatible pointer type

Question

I'm learning C. I tried to solve the following problem, but I had several problems.

I do not control the chain linked list with pointers.

Here's the problem:

We want to write functions for managing the employees of a company. An employee is defined by his name (character string), his personnel number (integer), the number of hours worked (real), and the hourly rate (actual).

1. Define the Employee data type
2. Functions:

• saisirEmploye; which allows you to enter an employee from the keyboard
• affichEmploye; which displays an employee on the screen
• calculSalaire; which calculates and returns the employee's salary (salary = nbh * rate_h)

3. We now want to store a set of employees in a linked list, define for this the node and ListEmp data types.

• ajouterEmploye; which allows you to add a new employee to the list (the addition can be do at the beginning or at the end of the list, your choice)
• saisirListEmploye; which allows you to enter from the keyboard a list of n employees.
• affichListEmploye; which displays a list of employees on the screen.
• totalSalaire; which calculates and returns the total salary of all the employees on the list

4. Write a main function performing the following operations:

• declare a list of employees
• enter the number of employees using the keyboard
• enter list
• calculate the total salary of all employees
• display the contents of the list, as well as the total salary

My code:

#include <stdio.h>
#include <stdlib.h>

typedef struct
{
 char nom[20];
 int mat;
 float ht;
 float tx ;
}Employe;


typedef struct
{
    Employe *employe;
    struct ListEmp *suivant;
}ListEmp;

typedef struct 
{
    ListEmp *premier;
}Elements;


void saisirEmploye(Employe *e)
{
    printf("Sasir le nom \n");
    scanf("%s",e->nom);
    printf("Saisir le matricule \n");
    scanf("%d",&e->mat);
    printf("Saisir le nombre d’heures travaillees \n");
    scanf("%f",&e->ht);
    printf("Saisir le taux horaire \n");
    scanf("%f",&e->tx);

}

void afficheEmp(Employe e)
{
    printf("Nom : %s | Matricule : %d | Nombre d’heures travaillees : %f | Taux horaire : %f \n",e.nom,e.mat,e.ht,e.tx);
}

float calculSalaire(Employe e)
{
    float salaire = 0;
    salaire = (e.ht)*(e.tx) ;
    return salaire;
}

Elements *init()
{
    ListEmp *liste = malloc(sizeof(ListEmp));
    Elements *elements = malloc(sizeof(Elements));

    if (liste == NULL || elements == NULL)
    {
        exit(EXIT_FAILURE);
    }

    liste->employe = NULL;
    liste->suivant = NULL;
    elements->premier = liste;

    return elements;
}


void ajouterEmp(Elements *elements, Employe *employe)
{
    /* Création du nouvel élément */
    ListEmp *nouveau = malloc(sizeof(*nouveau));
    
    if (elements == NULL || nouveau == NULL)
    {
        exit(EXIT_FAILURE);
    }
    
    nouveau->employe = employe;

    /* Insertion de l'élément au début de la liste */
    nouveau->suivant = elements->premier;
    elements->premier = nouveau;
}


int main()
{
 // Employes e;
 // e.tete=NULL;
 // int n=0;
 // float t=0;
 // printf("Donner le nombre des Emplyes \n"); // saisie du nbr des employes
 // scanf("%d ",&n);
 // saisirListEmp(&e,n); // saisie de la liste
 // t=totalSalaire(e); //calcule du salaire totale
 // afficheList(e); // affichage du contenu
 // printf("le salaire totale=%f ",t); // affichage du salaire
 
 
 Employe e;
 printf("Saisr un emplye \n");
 saisirEmploye(&e);
 //printf("Nom emplye : %s \n", e.nom);
 afficheEmp(e);
 printf("Salaire : %f",calculSalaire(e));
 
 Elements *maListe = init();
 ajouterEmp(maListe,e)
 
 return 0;
}

Edited code:

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

typedef struct
{
    char nom[20];
    int mat;
    float ht;
    float tx;
} Employe;


typedef struct Elem
{
    Employe employe;
    struct Elem *prev;
    struct Elem *next;
}Elem;

typedef struct
{
    Elem *first;
    Elem *last;
}ListEmp;


void saisirEmploye(Employe *e)
{
    printf("Sasir le nom \n");
    scanf("%s",e->nom);
    printf("Saisir le matricule \n");
    scanf("%d",&e->mat);
    printf("Saisir le nombre d’heures travaillees \n");
    scanf("%f",&e->ht);
    printf("Saisir le taux horaire \n");
    scanf("%f",&e->tx);

}

void afficheEmp(Employe e)
{
    printf("Nom : %s | Matricule : %d | Nombre d’heures travaillees : %f | Taux horaire : %f \n",e.nom,e.mat,e.ht,e.tx);
    printf("\n");
}

float calculSalaire(Employe e)
{
    float salaire = 0;
    salaire = (e.ht)*(e.tx) ;
    return salaire;
}


ListEmp *init()
{
    ListEmp *listEmp = malloc(sizeof(ListEmp));
    Elem *elem = malloc(sizeof(Elem));
    Employe employe;

    if (listEmp == NULL || elem == NULL)
    {
        exit(EXIT_FAILURE);
    }
    strcpy(employe.nom, "Hamza");
    employe.mat = 123;
    elem->employe = employe;
    elem->next = NULL;
    listEmp->first = elem;

    return listEmp;
}

void auDebut(ListEmp *listEmp, Employe employe)
{
    printf("1 Au debut \n");
    Elem *elem = (Elem*)malloc(sizeof(Elem));
    elem->employe = employe;
    elem->next = listEmp->last;
    elem->prev = NULL;
    if(listEmp->last)
        listEmp->last->prev = elem;
    else
        listEmp->last = elem;
    listEmp->first = elem;
}

void aLaFin(ListEmp *listEmp, Employe employe)
{
    
    Elem *elem = (Elem*)malloc(sizeof(Elem));
    elem->employe = employe;
    elem->prev = listEmp->first;
    elem->next = NULL;
    if(listEmp->first)
        listEmp->first->next = elem;
    else
        listEmp->first = elem;
    listEmp->last = elem;
    
//    Elem *elem = (Elem*)malloc(sizeof(Elem));
//    if(!elem) exit(EXIT_FAILURE);
//    elem->employe = employe;
//    elem->next = listEmp->first;
//    listEmp->first = elem;
}





void ajouterEmploye(ListEmp *listEmp, Employe employe)
{
    char element;
    printf("Voulez-vous ajouter le nouvel employe au début de la liste d ou a la fin de la liste f ? \n");
    scanf(" %c", &element);
    if (element == 'd')
        //printf("Au debut \n");
        auDebut(listEmp,employe);
    else if (element == 'f')
        //printf("A la fin \n");
        aLaFin(listEmp,employe);
}

void saisirListEmploye(ListEmp *listEmp, int n)
{
    Employe employe;
    for(int i=1;i<=n;i++)
    {
        printf("Employe %d\n",i);
        saisirEmploye(&employe);
        ajouterEmploye(listEmp,employe);
    }
}

void affichListEmploye(ListEmp *listEmp)
{
    Elem *i = listEmp->first;
    while(i != NULL)
    {
        afficheEmp(i->employe);
        i = i->next;
    }
}


float totalSalaire(ListEmp *listEmp)
{
    float total = 0;
    Elem *i = listEmp->first;
    while (i != NULL)
    {

        total += calculSalaire(i->employe);
        i = i->next;
    }
    return total;
}

int main()
{
 
    Employe e;
    int n;
    //printf("Saisr un emplye \n");
    //saisirEmploye(&e);
    //printf("Nom emplye : %s \n", e.nom);
    //afficheEmp(e);
    //printf("Salaire : %f",calculSalaire(e));
    //printf("\n\n");
    
    ListEmp *listEmp = init();
    //ajouterEmploye(listEmp,e);
    
    printf("Combien d'employes souhaitez-vous ajouter ?\n");
    scanf("%d",&n);
    saisirListEmploye(listEmp,n);
    
    affichListEmploye(listEmp);
    printf("Le salaire total de tous les employés de la liste est : %f", totalSalaire(listEmp));

    return 0;
}

The error:

main.c: In function ‘ajouterEmp’:
main.c:87:22: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
     nouveau->suivant = elements->premier;
                      ^
main.c: In function ‘main’:
main.c:114:21: error: incompatible type for argument 2 of ‘ajouterEmp’
  ajouterEmp(maListe,e)
                     ^
main.c:76:6: note: expected ‘Employe * {aka struct  *}’ but argument is of type ‘Employe {aka struct }’
 void ajouterEmp(Elements *elements, Employe *employe)
      ^~~~~~~~~~
main.c:116:2: error: expected ‘;’ before ‘return’
  return 0;
  ^~~~~~

Can you help me please? Thanks!

Answer 1

About your type errors: There is defined

typedef struct {
    char  nom[20];
    int   mat;
    float ht;
    float tx;
} Employe;

but later you used Employes instead of Employe, for example in

void ajouterEm (Employes *e, Elem nemp) { /* ... */ }

Same for Elements and Elem here. This is why you get unknown type errors. In

ajouterEmp(maListe, e)

there must also be an semicolon after the instruction. Attention should also be paid to where pointers (for example Employes*) and where entire structures (without *) are passed to the function.

Edit after this errors has been fixed:

Within

typedef struct{
    Employe *employe;
    struct ListEmp *suivant;
} ListEmp;

the type name ListEmp is already used in the definition in suivant, but is only defined in the line below. Use

typedef struct _ListEmp {
    Employe *employe;
    struct _ListEmp *suivant;
} ListEmp;

instead. The struct gets the name _ListEmp and then you define struct _ListEmp as ListEmp. For the third error at

ajouterEmp(maListe, e)

a pointer must be passed, but Employe e is a whole data structure. Write

ajouterEmp(maListe, &e);

instead and add the semicolon.