Weird shapes as output( Strings)- C language - string

Question

So i have a problem. I have to separate the first name, last name and hostname of email.
For example:
zephyr.extreme#gmail.com>> Input
Output=
First name= Zephyr
Last name= extreme
Host Name= gmail.com
I am not getting the desired result. I am getting some weird shapes as output.
Code:
#include <stdio.h>
int main()
{
char email[40], first[20],last[20],host[30];
printf("Enter the email= ");
gets(email);
int i;
while(email[i]!='\0')
{
while(email[i]!='.')
{
first[i]=email[i];
i++;
}
while(email[i]!='#')
{
last[i]=email[i];
i++;
}
while(email[i]!='\0')
{
host[i]=email[i];
i++;
}
}
puts(first);
puts(last);
puts(host);
}

Answer 1

Assuming the format will always be first.last#host..., use this code:
#include <stdio.h>
#include <string.h>
int main()
{
char email[40], first[20],last[20],host[30],name[40];
int firstDot,atSymbol;
int i;
int length;
char *token;
printf("Enter the email= ");
gets(email);
length = strlen(email);
for(i=0;i<length;i++){
if(email[i]=='.')
{
firstDot = i;
}
else if(email[i]=='#')
{
atSymbol = i;
}
}
strncpy(name,email,atSymbol);
name[atSymbol]= '\0';
token = strtok(name, ".");
/* walk through other tokens */
while( token != NULL )
{
printf( "%s\n", token );
token = strtok(NULL, ".");
}
strncpy(host,email+atSymbol,length-atSymbol);
host[length-atSymbol] = '\0';
puts(host);
}

Answer 2

So i updated the code, now the only problem is the last output.
After host name= gmail.com prints, but then some extra shapes are also printing. These are smile face and some weird symbols.
Code:
#include <stdio.h>
int main()
{
char email[40], first[20],last[20],host[30];
printf("Enter the email= ");
gets(email);
int i=0,j;
while(email[i]!='.')
{
first[i]=email[i];
i++;
}
i=0;
while(email[i]!='#')
{
last[i]=email[i];
i++;
}
j=i;
i=0;
while(email[j]!='\0')
{
host[i]=email[j];
j++;
i++;
}
printf("First Name= ");
puts(first);
printf("Last name= ");
puts(last);
printf("Host name= ");
puts(host);
}

Answer 3

C strings (char pointers) should be null-terminated. This means your string needs a '\0' character at its end so that string manipulation functions such as puts or strlen know where they end, in constrast to other languages where the string's length is stored together with it. The "weird shapes" you are seeing are just random data stored after the end of the string being interpreted as characters. When you call puts it just keeps outputting bytes-as-characters until it randomly finds a byte with value '\0'
You can solve this by adding a '\0' character to the end of the string after each of the blocks where you write a string.
while(email[i]!='.')
{
first[i]=email[i];
i++;
}
email[i] = '\0'; //same thing as email[i] = 0; but using a char makes what
//you're doing clearer