Hello , I think I have a problem with the pointers , I need help ! , can you fix my code

Question

#include <stdio.h> 

void chercherVal(int tab[], int N, int A, int *pos, int *nb_occ) { 
    int i = 0; 
    while (i < N) {
        if (tab[i] == A) { 
            *pos = i;
            *nb_occ = *nb_occ + 1; 
        } 
        i++; 
    } 
    printf("la position est %d et le nombre d'occurence est %d", pos, nb_occ); 
} 

int main() {
    int pos = -1, nb_occ = 0; 
    char A;
    int i, N;
    int tab[100]; 
    printf("saisir le nombre d'elements de tab :"); 
    scanf("%d", &N); 
    for (i = 0; i < N; i++) { 
        printf("saisir l'element %d du tableau tab :", i + 1); 
        scanf("%d", &tab[i]);
    }
    printf("saisir la valeur a rechercher :"); 
    scanf("%s", &A); 
    chercherVal(tab, N, A, &pos, &nb_occ); 
}

Answer 1

Here is one pointer problem (or lack of)

printf("la position est %d et le nombre d'occurence est %d", pos, nb_occ);

should be

printf("la position est %d et le nombre d'occurence est %d", *pos, *nb_occ);

The compiler should have warned that the wrong argument types are being passed.

Answer 2

Reading a string with scanf("%s", &A); into a single char has undefined behavior because scanf() will store the bytes and a null terminator, writing beyond the destination variable.

You should either make A and int and read a number: scanf("%d", &A);

Or you should read a single char with scanf(" %c", &A); (note the space before the % to skip pending white space, including the newline left in the standard input by previous calls to scanf().

Here is a modified version:

#include <stdio.h> 

void chercherVal(const int tab[], int N, int A, int *posp, int *nb_occp) { 
    int pos = -1, occ = 0;
    for (int i = 0; i < N; i++) {
        if (tab[i] == A) { 
            occ++; 
            if (pos < 0) { /* only store the first position */
                pos = i;
            }
        } 
    } 
    /* always store the return values */
    *posp = pos;
    *nb_occp = occ;
} 

int main() {
    int tab[100];
    int N, A, pos, nb_occ; 

    printf("saisir le nombre d'elements de tab : "); 
    if (scanf("%d", &N) != 1)
        return 1;
    if (N > 100) /* prevent buffer overflow */
        N = 100; 
    for (int i = 0; i < N; i++) { 
        printf("saisir l'element %d du tableau tab : ", i + 1); 
        if (scanf("%d", &tab[i]) != 1)
            return 1;
    }
    printf("saisir la valeur a rechercher : "); 
    if (scanf("%d", &A) != 1)
        return 1;
    chercherVal(tab, N, A, &pos, &nb_occ); 
    printf("la position est %d et le nombre d'occurences est %d\n", pos, nb_occ); 
    return 0;
}