having trouble with global variables in C

Question

It seems that I can not save a global variable any help? Here is the part of the code that seems to be the trouble: PS: the (#include are included)

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

void signup_user(char nameuser[10], char suruser[10],
                 char addressu[20], char usernameu[10],
                 char passuser[5]);
extern char nameuser[10] = "", suruser[10] = "",
            addressu[20] = "", usernameu[10] = "",
            passuser[5] = "";

int main {
    signup_user(nameuser, suruser, addressu, usernameu, passuser);
}

void signup_user(char nameuser[10], char suruser[10],
                 char addressu[20], char usernameu[10],
                 char passuser[5]) { //synarthsh signup
    printf("give name: ");
    scanf(" %s", &nameuser); //dinei onoma

    printf("give surname: ");
    scanf(" %s", &suruser); //dinei epitheto

    printf("give address: ");
    scanf(" %s", &addressu);

    printf("give username: ");
    scanf(" %s", &usernameu); //dinei username

    printf("give password: ");
    scanf(" %s", &passuser);
}

Answer 1

Your code will not compile. Do not use keywords you do not understand (extern). Format your code properly. Learn about arrays and pointers.

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


void signup_user(char *, char *,char *, char *, char *);
char nameuser[10]="", suruser[10]="", 
     addressu[20]="", usernameu[10]="", passuser[5]="";




int main(void )
{
    signup_user(nameuser, suruser, addressu, usernameu, passuser);
}


void signup_user(char nameuser[10], char suruser[10], char addressu[20], char usernameu[10], char passuser[5]) 
{
    printf("give name: ");
    scanf(" %9s", nameuser);//dinei onoma

    printf("give surname: ");
    scanf(" %9s", suruser);//dinei epitheto

    printf("give address: ");
    scanf(" %19s", addressu);

    printf("give username: ");
    scanf(" %9s", usernameu);//dinei username

    printf("give password: ");
    scanf(" %4s", passuser);
}

Also you should check the return value of scanf