C question;how do I put struct in function?

ngan_yine · 02-04-2005, 05:05 PM

Hi
I know this may sound very silly but I am newbie and this doubt seem to bother me much;
Here's my question :
I had been trying to write a function to print out the struction which hold a mailing list for starter and I could only do it in following way:

Code:

#include <stdio.h>
#include <string.h>
struct mailing {
        char name[60];/*First name ,last name*/
        char address[60];/*Two line of street address*/
        char city[40];
        char state[2];/*Two character abbreviation*/
        int zip;/*Numberic zip code*/
}list = {
        "something",
        "somethingl",
        "something",
        "something",
        70295404,};
void write(char names[60],char addresss1[60],char citys[40],char states[2],int zips){

        printf("The name is %s\n",names);
        printf("The first address is %s\n",addresss1);
        printf("The city name is %s\n",citys);
        printf("The state name is %s\n",states);
        printf("The zip code is %d\n",zips);
}

int main(){
        /*debug*/printf("The name is %s\n",list.name);
        /*debug*/write(list.name,list.address,list.city,list.state,list.zip);
        return (0);
}

And I was wondering if there are other way around to do this .Such as declaring struct mail in function parameter but my gcc compiler doesn't seem to allow me this.
Thanks for reading;

Ephracis · 02-04-2005, 05:16 PM

I have also checked this code and it can compile and run. Just a note, I added an extra char to the state to hold the null-char. I don't know if you want this but unless you have a null-char you can't treat it as a string, just as a array of chars.

Code:

#include <stdio.h>
#include <string.h>
struct mailing {
        char name[60];          // full name
        char address[60];       // two line of street address
        char city[40];
        char state[3];          // two char abbr (+ null-char)
        int zip;                // zipcode
} list = {
        "something",
        "something",
        "something",
        "so",
        70295404,
};

void write(struct mailing list) {

        printf("The name is %s\n",list.name);
        printf("The first address is %s\n",list.address);
        printf("The city name is %s\n",list.city);
        printf("The state name is %s\n",list.state);
        printf("The zip code is %d\n",list.zip);
}

int main() {
        printf("The name is %s\n",list.name);
        write(list);
        return (0);
}

ngan_yine · 02-04-2005, 06:03 PM

Thank U! This is How I wanted to write in the first place .I want to write a function
which could take struct as struct in function and print out the display .
I had tried to do something like :

Code:

void write(struct mailing{char name[60],char address[60] and so on}list;)
          printf("%s\n",name.list);
          /*and so on*/}

I never knew that I could declare as

Code:

void write(struct mailing list)

Thank man ,I am such a newbie in programming

jonaskoelker · 02-05-2005, 08:31 PM

Hi.

I recommend that you read "The C Programming Language" [Kernighan (sp?) & Ritchie] -- the "C bible";

Jonas

ngan_yine · 02-06-2005, 09:26 PM

Thanks man
I just download that one form internet ,I had been reading O'reaily 's Parctical C.

chrism01 · 02-06-2005, 10:13 PM

FYI, for large structs and/or repeated calls in a loop, it's usual to pass a ptr to the struct instead; lower overhead (speed/mem) when running.

JurajPsycho · 02-07-2005, 04:57 PM

why not to use typedef ?

Code:

typedef struct mailing
{
...
}list;

you wouldn't have to use

Code:

void write(struct mailing list)

but 

void write(mailing list)

J.

itsme86 · 02-07-2005, 05:06 PM

I believe you mean void write(list list)

jschiwal · 02-07-2005, 05:24 PM

If I could recommend a book to read, it would be
Linux Programming by Example : The Fundamentals

http://www.amazon.com/exec/obidos/AS...431031-0552630

This books uses the code from familiar commands like 'cat' and 'ls'.
It does a good job of showing how gnu commands are written and why.

skoona · 02-08-2005, 07:31 PM

Code:

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

typedef struct mailing {
        char name[60];         /*First name ,last name*/
        char address[60];      /*Two line of street address*/
        char city[40];
        char state[3];         /*Two character abbreviation*/
        int zip;               /*Numberic zip code*/
} mlist, *P_list;

int fn_write( P_list plist )
{
  int  i_rc = 0;
  
  i_rc = fprintf ( stdout, 
                   "The name is %s\n"               /* notice careful use of comma's */
                   "The first address is %s\n"
                   "The city name is %s\n"
                   "The state name is %s\n"                   
                   "The zip code is %d\n",
                   plist->name,
  	           plist->address,
                   plist->city,
                   plist->state,
                   plist->zip
                 );
   
  return i_rc;
}

int main(int argc, char *argv[])
{
  int   i_rc = 0;
  mlist mylist = {
                  "something",
                  "somewhere",
                  "someplace",
                  "SW",
                   70295404
                 };

  printf ( "The name is %s\n", mylist.name );
  i_rc = fn_write ( &mylist );

  printf ( "The text buffer was %d in length\n", i_rc );

  return (0);
}

Using a pointer to the structure is a little more involved, but still straight forward.

note: compiled with $ gcc -Wall -W1 -o prog -c prog.c

James,

ngan_yine · 02-09-2005, 02:54 PM

Thank you so much ,guy ,This really help me a lot .