int make_friends(const char *name1, const char *name2, User *head) {
    User *curr = head;
    User *user1 = NULL;
    User *user2 = NULL;
    //traverses through list, assigns curr to user 1 and user2
    if(strcmp(name1, name2)==0){
        return 3;
    }
    else{
        while(curr != NULL){
            if(strcmp(curr ->name, name1)==0 ){
                user1 = curr;
            }
            if(strcmp(curr ->name, name2)==0 ){
                user2 = curr;
            }
        curr= curr->next;
        }
        if(user1 == NULL ||  user2 ==NULL){
            return 4;
        }
        else{
            for(int x =0;x<MAX_FRIENDS;x++){
                if(strcmp(user1->friends[x]->name, name2)==0){
                    return 1;
                }
           }
            for(int i =0; i<MAX_FRIENDS; i++){
                if(user1->friends[i]==0){
                    user1->friends[i]= user2;
                    break;
                }
                else{
                    return 2;
                }
            }
            for(int j= 0;j<MAX_FRIENDS;j++){
                if(user2->friends[j]==0){
                    user2->friends[j]= user1;
                    break;
                    }
                else{
                    return 2;
                }
            }
            return 0;
        }
    }
}
replace first 0 in friend array of User name1 with User name2 and replace the first 0 in friend array of User name 2 with User name1