the function does not update the parameter C - c

Question

i have this function that extract the first name and the gendre form a file combined and then seperate them
for example the function extract "Aaliyah,F" and the separate them as prenom = Aaliyah and genre = F
the problem is that the function does not update the genre value and still at NULL
so for this code
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
int AleaNombre(int min, int max) {
return (rand() % (max - min + 1)) + min;
}
void recuperer_prenom(char genre , char prenom[20] ) {
FILE* f2 = fopen("C:\\Users\\PC PRO DZ\\Desktop\\Projects\\C\\TP essai\\prenom.txt", "r");
fseek(f2, 0, SEEK_END);
int length = ftell(f2);
fseek(f2, 0, SEEK_SET);
char line1[length + 1];
fgets(line1, length + 1, f2);
int i = AleaNombre(1, 100);
int cpt = 0;
char* tok = strtok(line1, " ; ");
cpt++;
while (cpt != i) {
tok = strtok(NULL, " ; ");
cpt++;
}
//separer le prenom et le genre tel que prenom,genre et le genre est le dernier caractere en utilisant strtok
char* tok2 = strtok(tok, ",");
strcpy(prenom, tok2);
tok2 = strtok(NULL, ",");
genre = tok2[0];
printf("%s %c", prenom, genre); // the result is for example: "Aaliyah F"
rewind(f2);// ^ ^
fclose(f2);// |prenom| |genre|
}
int main () {
srand (time(NULL));
char prenom[20];
char genre;
recuperer_prenom(genre, prenom);
printf ("%s %c", prenom, genre);// however the result here is "Aaliyah"
return 0;
}
i tried changing the way that the prenom and genre are separated and change the type of genre from char to a sting but didn'f fixe it

Answer 1

I have removed the random part and created a struct to store your fields:
You should pass by reference as said in comment
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#define MAXLINE 256
typedef struct data {
char prenom[20];
char genre;
} data;
void recuperer_prenom(data *d) {
FILE* f2 = fopen("prenom.txt", "r");
char line1[MAXLINE];
fgets(line1, MAXLINE, f2);
char* tok = strtok(line1, " ; ");
//separer le prenom et le genre tel que prenom,genre et le genre est le dernier caractere en utilisan>
char* tok2 = strtok(tok, ",");
strcpy(d->prenom, tok2);
tok2 = strtok(NULL, ",");
d->genre = tok2[0];
printf("%s %c\n", d->prenom, d->genre); // the result is for example: "Aaliyah F"
fclose(f2);// |prenom| |genre|
}
int main () {
data d;
recuperer_prenom(&d);
printf ("%s %c\n", d.prenom, d.genre);// however the result here is "Aaliyah"
return 0;
}