Searching for a string in an array without strcmp - arrays

Question

I have a struct in this form:
typedef struct student{
double student_no;
char name[50];
char surname[50];
double phone_no;
char mail[50];
};
struct student person[100];
printf("Student's mail address: ");
scanf("%s", person[i].mail); //i use codeblocks and it works without the sign &
First I create an array of mails. Then I get a mail for user, then check if it is in my array that I created in the first place. I have to do it without strcmp(), and that's where I get stuck. Here is what I've tried so far:
char *e1, *e2;
int comp;
typedef struct info{
char email[50];
};
struct info mailaddress[0];
printf("Enter the mail address to search: ");
scanf("%s", mailaddress[0]);
for (int i = 0; i < u; i++) {
for (int j = i + 1; j < u; j++) {
e1 = person[i].mail;
e2 = mailaddress[j].email;
comp = 0;
while (*e1 && *e2) {
if (*e1 != *e2) {
comp = *e1 - *e2;
break;
}
++e1;
++e2;
}
if (comp == 0)
printf("%s\t %s %15.lf %15.lf %s\n",
person[i].name,
person[i].surname,
person[i].student_no,
person[i].phone_no,
person[i].mail);
}
}

Answer 1

Try like this
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <conio.h>
#include <string.h>
#define NO_MAX 20
#define NAME_MAX 20
#define SURNAME_MAX 20
#define PHONE_NO_MAX 20
#define MAIL_NO_MAX 50
struct student{
char student_no[NO_MAX + 1];
char name[NAME_MAX + 1];
char surname[SURNAME_MAX + 1];
char phone_no[PHONE_NO_MAX + 1];
char mail[MAIL_NO_MAX + 1];
struct student *ptr_next;
};
struct student *ptr_head = NULL;
struct student *ptr_position;
void enter_item(char *ptr_label, char *ptr_result, int max){
// enter item until pressed enter to finished
char tmp[256];
do {
printf("%s: ", ptr_label);
gets(tmp);
} while((strlen(tmp) > max));
strcpy(ptr_result, tmp);
}
void enter_list(void) {
char more;
struct student *ptr_new;
do{
// order dynamic memory
ptr_new = (struct student *) malloc(sizeof(struct student));
if(ptr_new) {
// enter item
enter_item("student_no", ptr_new->student_no, NO_MAX);
enter_item("name", ptr_new->name, NAME_MAX);
enter_item("surename", ptr_new->surname, SURNAME_MAX);
enter_item("phone_no", ptr_new->phone_no, PHONE_NO_MAX);
enter_item("mail", ptr_new->mail, MAIL_NO_MAX);
// next item
ptr_new-> ptr_next = ptr_head;
ptr_head = ptr_new;
// enter item again or not
printf("- again(Y/N)? -");
do{
more = toupper(getch());
} while(!(more=='Y' || more=='N'));
printf(" %c\n\n", more);
}
else {
printf("Memory isn't enough!\n");
break;
}
} while(more == 'Y');
}
void search_mail() {
// enter mail
struct student *ptr_search;
ptr_search = (struct student *) malloc(sizeof(struct student));
enter_item("mail searching", ptr_search->mail, MAIL_NO_MAX);
char *mail = ptr_search->mail;
// searching mail
ptr_position = ptr_head;
while(ptr_position) {
if(strcmp(mail, ptr_position->mail) != 0) {
ptr_position = ptr_position-> ptr_next;
}
else {
printf("Email is found\n");
return;
}
}
printf("Email isn't found!\n");
}
int main()
{
enter_list();
search_mail();
return 0;
}
Result:

Answer 2

bool streq(char *a, char *b)
{
while (*a && *b && *a != *b)
a++, b++;
return !*a && !*b;
}