Help doing an e-mail program in c...

**Emmanuel Delaha** · 12-30-2004

Originally Posted by Tyler_Durden

so I have to make a main(void) inside my comandom.c, right? Or that main is the one from progmail.c, and the void comandom is from comandom.c ?

No. I was just an example. The general idea is that when you use a structure, it's good design to pass the address of it to the functions.

The address can be the address of some object

Code:

void fa (void)
{
   T o;

   fb (&o);
}

or the address got from a parameter

Code:

void fa (T *po)
{
   fb (po);
}

or from malloc():

Code:

void fa (void)
{
   T *po = malloc  (sizeof *po);

   if (po != NULL)
   {
      fb (po);
      free (po),  po = NULL;
   }
}

**Tyler_Durden** · 12-30-2004

thanks a lot people... you are being really helpful...

Now I'm going to try to do comandoq.c, which has to save all emails written when "q" is pressed...
I think it must be something like this...

Code:

#include <stdio.h>

FILE *fp;

fp = fopen("mail.txt","a");

fprintf(fp,"From:%s\n",MAIL.from);
fprintf(fp,"To:%s\n",MAIL.to);
fprintf(fp,"Subject:%s\n",MAIL.sub);
fprintf(fp,"Message:%s\n",MAIL.msg);
fprintf(fp,"\n");

fclose(fp);

}

but now I have a doubt, if I write more than one e-mail will it save all of them in the file?
thanks =)

**sand_man** · 12-30-2004

Not sure what you mean. Put the reading and writing in a loop. Read the record(or whatever I came late to the thread), do what you gotta do then write the record to the file. Then loop back to the top and read the next record.

**Tyler_Durden** · 12-30-2004

Code:

// this is comandom.c
#include <stdio.h>    /* para funcoes como printf, scanf, etc */
#include <stdlib.h>   /* para a funcao exit */ 
#include <string.h>   /* para funcoes relacionadas com strings */
#include "progmail.h"

void comandom(MAIL *ptr)
{
  printf("From:   \n"); fgets(ptr->from,sizeof ptr->from, stdin);
  printf("To:     \n"); fgets(ptr->to,sizeof ptr->to, stdin);
  printf("Subject:\n"); fgets(ptr->sub,sizeof ptr->sub, stdin);
  printf("Message:\n"); fgets(ptr->msg,sizeof ptr->msg, stdin);
}

I dunno why but the program isn't asking me to insert the "From"...
when I press "m" the output is:
From:
To:
(insert to)
.---------

it skips the from, and then when I test it with "L" the from is empty...

**Emmanuel Delaha** · 12-30-2004

Originally Posted by Tyler_Durden

Code:

void comandom(MAIL *ptr)
{
  printf("From:   \n"); fgets(ptr->from,sizeof ptr->from, stdin);
  printf("To:     \n"); fgets(ptr->to,sizeof ptr->to, stdin);
  printf("Subject:\n"); fgets(ptr->sub,sizeof ptr->sub, stdin);
  printf("Message:\n"); fgets(ptr->msg,sizeof ptr->msg, stdin);
}

I dunno why but the program isn't asking me to insert the "From"...
when I press "m" the output is:
From:
To:
(insert to)
.---------

it skips the from, and then when I test it with "L" the from is empty...

Probably because you have a pending '\n' in stdin. I guess you are using getchar() or scanf() in you menu...

All inputs should be done with fgets().

**Tyler_Durden** · 12-30-2004

ah ok...that problem is solved now..
so the next step is to make some cycles in the writing and reading of the emails...but how can I make the loop in the writing so I get each mail and its characteristics into different variables..
for example in the first mail I write when I open the program :
subject: sub1
from : from1
message :msg1

then when I write the second email, its subject is sub2, and its from is from2,etc....
how can I do that? I can't manage to do that....
thanks a lot for all your help till now, i'm really appreciated...

EDIT- because right now, when I write a new email, the previous one is overwritten...

**itsme86** · 12-30-2004

You can use an array.

Something like this:

Code:

{
  MAIL m[10];
  int i;

  for(i = 0;i < 10;++i)
  {
    // Get values for this mail message here

    commandom(&m[i]);
  }
}

**Tyler_Durden** · 12-30-2004

Originally Posted by itsme86

You can use an array.

Something like this:

Code:

 void comandom(MAIL *ptr)
{
  MAIL m[10];
  int i;

  for(i = 0;i < 10;++i)
  {

  printf("From:   \n"); fgets(ptr->from,sizeof ptr->from, stdin);
  printf("To:     \n"); fgets(ptr->to,sizeof ptr->to, stdin);
  printf("Subject:\n"); fgets(ptr->sub,sizeof ptr->sub, stdin);
  printf("Message:\n"); fgets(ptr->msg,sizeof ptr->msg, stdin);
}

    comandom(&m[i]);
  }
}

so, should my comandom.c be something like this?

**Emmanuel Delaha** · 12-30-2004

Originally Posted by Tyler_Durden

so the next step is to make some cycles in the writing and reading of the emails...but how can I make the loop in the writing so I get each mail and its characteristics into different variables..
Why would you do that ?

- Get the info
- Save the info

You should open your file in "a" mode. It will append to the end of it (or create it if non-existent)

**Tyler_Durden** · 12-30-2004

but the problem is that the mails should only be saved when "q" is pressed and not when I insert the values...

**Emmanuel Delaha** · 12-30-2004

Originally Posted by Tyler_Durden

but the problem is that the mails should only be saved when "q" is pressed and not when I insert the values...

So you want to input several mails before saving them ? Unsafe, but if you insist, you can use an array of structs as mentionned elswere.

Of course a static array has a limited size. If you want a sky-is-the-limit solution, you want a flexible array (malloc() / realloc()) or a linked list...

**Tyler_Durden** · 12-30-2004

Originally Posted by Emmanuel Delaha

So you want to input several mails before saving them ? Unsafe, but if you insist, you can use an array of structs as mentionned elswere.

Of course a static array has a limited size. If you want a sky-is-the-limit solution, you want a flexible array (malloc() / realloc()) or a linked list...

EDIT - ignore that, lol...It doesn't need to save only when "q" is pressed,lol....less a problem..now I'll try and fprintf all of the mails into the "mail.txt" file...wish me luck

sorry if I'm being too boring and I'm asking for too much help, but I would really like to get the necessary grade to proceed...

**Tyler_Durden** · 12-30-2004

Ok...the comandom.c is edited and know saves the mail info into the "mail.txt" file but there is a problem..
I need the format of the mail.txt file to be like this:
To:{[email protected]}
From:{[email protected]}
Subject:{blabla}
{bla bla bla bla}

so for that my fprintfs are this way:
fprintf(fp,"{%s}",ptr->to);
...
..

but the mail.txt program turns out like this:
to:{[email protected]
}
From{[email protected]
}
Subject:{ggd
}
etc...

**Sebastiani** · 12-30-2004

>> but the mail.txt program turns out like this:

you need to remove the newline retrieved from fgets().

>> but I would really like to get the necessary grade to proceed...

if you *really* wanted that grade you would have started a lot sooner than this.

**Stack Overflow** · 12-30-2004

Hello,

Keep in mind fgets reads the "newline" character '\n' and puts it at the end of the string as an extra character. There are ways of removing the last character from your string. A simple way is the following:

Code:

#include <stdio.h>

int main() {
	char s[25], *pch;

	fgets(s, 24, stdin);

	// Search for newline
	if (pch = strrchr(s, '\n'))
		*pch = '\0';

	printf("%s", s);

	return 0;
}

There are other ways to accomplish this also. There was once a discussion about this in great detail. You can find the thread here: Using fgets, removing last character.

- Stack Overflow