Question

Using C(89). A fashion retailer has decided to provide discount codes to teachers and students during a promotional event. The first step is to verify the teacher/student status of people requesting discount code by their email addresses. They will check if the email addresses end with ".edu" and find the domain name if it does before further verification. Write a program to find the domain name of an email address if the domain name ends with .edu. The program displays domain that ends with edu. If the input does not contain an email address that ends with .edu, the program should display a message that indicates it is not a valid email address for the discount code.

Example input/output:

Input: jennifer23@nyu.edu

Output: nyu.edu

Input: joeW19@mail.usf.edu

Output: mail.usf.edu

Input: johnA@facebook.com/

Output: Not a valid email address for the discount code

Your program should include the following function: int find_domain(char *s1, char *s2);

NOTE:

1) The find_domain function expects s1 to point to a string containing the input for an email address as a string and stores the domain to the string pointed by s2. If the email address does not end with .edu, s2 should contain an empty string. An empty string is a valid string with no characters except the null character. The function returns 1 if the email addresses ends with .edu in the domain, and returns 0 otherwise.

2) The find_domain function should use pointer arithmetic (instead of array subscripting). In other words, eliminate the loop index variables and all use of the [] operator in the function.

3) To read a line of text, use the read_line function (the pointer version):

}

int read_line(char *str, int n)

{

int ch; int i = 0;

while ((ch = getchar()) != '\n')

{ if (i < n)

{ *str++= ch;

i++;

}

}

* str = '\0'; /* terminates string */

return i; /* number of characters stored */

}

Answer 1

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

int read_line(char *str, int n) {

    int ch; int i = 0;
    while ((ch = getchar()) != '\n'){ 
        if (i < n) { 
            *str++= ch;
            i++;
        }
    }

    *str = '\0'; /* terminates string */
    return i; /* number of characters stored */
}

int find_domain(char *email, char *dest) {
    // first find @    int i =0;
    int len = strlen(email);
    while(*email) {
        if(*email == '@') {
            break;
        }
        email++;
        len--;
    }

    if(*email != '@' || len < 3) {
        *dest = '\0';
        return 0;
    }

    email++; // to remove @
    len--;

    char *domainStart = email;

    // check last 3 characters
    while(len != 3) {
        email++;
        len--;
    }

    if(strcmp(email, "edu") == 0) {
    strcpy(dest, domainStart);
    return 1;
    }

    *dest = '\0';
    return 0;
}

int main(void) {
    char str[100];
    char domain[100];

    printf("Enter email: ");
    int len = read_line(str, 100);

    if(find_domain(str, domain)) {
        printf("%s\n", domain);
    } else {
        printf("Invalid email\n");
    }
    return 0;
}

Please upvote, as i have given the exact answer as asked in question. Still in case of any concerns in code, let me know in comments. Thanks!