how to read differnet no. of lines from a file using c in linux?

[shermeenz]

the file which i have to read is:
From sms@localhost.l ocaldomain Wed May 16 10:46:03 2007
Return-Path: <sms@localhost. localdomain>
Received: from localhost.local domain (localhost.loca ldomain [127.0.0.1])
by localhost.local domain (8.13.5/8.13.5) with ESMTP id l4GEk300002418
for <sms@localhost. localdomain>; Wed, 16 May 2007 10:46:03 -0400
Received: (from sms@localhost)
by localhost.local domain (8.13.5/8.13.5/Submit) id l4GEk3H3002417
for sms; Wed, 16 May 2007 10:46:03 -0400
Date: Wed, 16 May 2007 10:46:03 -0400
From: sms@localhost.l ocaldomain
Message-Id: <200705161446.l 4GEk3H3002417@l ocalhost.locald omain>
To: sms@localhost.l ocaldomain
Subject: mail 1

030044444
1st mail to be sent
by sms

From sms@localhost.l ocaldomain Wed May 16 10:46:43 2007
Return-Path: <sms@localhost. localdomain>
Received: from localhost.local domain (localhost.loca ldomain [127.0.0.1])
by localhost.local domain (8.13.5/8.13.5) with ESMTP id l4GEkhdo002426
for <sms@localhost. localdomain>; Wed, 16 May 2007 10:46:43 -0400
Received: (from sms@localhost)
by localhost.local domain (8.13.5/8.13.5/Submit) id l4GEkhRa002425
for sms; Wed, 16 May 2007 10:46:43 -0400
Date: Wed, 16 May 2007 10:46:43 -0400
From: sms@localhost.l ocaldomain
Message-Id: <200705161446.l 4GEkhRa002425@l ocalhost.locald omain>
To: sms@localhost.l ocaldomain
Subject: 2nd mail


09888766
2nd mail to be sent
for df

From sms@localhost.l ocaldomain Wed May 16 10:47:55 2007
Return-Path: <sms@localhost. localdomain>
Received: from localhost.local domain (localhost.loca ldomain [127.0.0.1])
by localhost.local domain (8.13.5/8.13.5) with ESMTP id l4GEltPQ002436
for <sms@localhost. localdomain>; Wed, 16 May 2007 10:47:55 -0400
Received: (from sms@localhost)
by localhost.local domain (8.13.5/8.13.5/Submit) id l4GEltF0002435
for sms; Wed, 16 May 2007 10:47:55 -0400
Date: Wed, 16 May 2007 10:47:55 -0400
From: sms@localhost.l ocaldomain
Message-Id: <200705161447.l 4GEltF0002435@l ocalhost.locald omain>
To: sms@localhost.l ocaldomain
Subject: 3rd mail



099888776
3rd mail for user
gsg

from this file i have to read lines below the "subject:" from there i have to read number and then the written e-mail right now i am able to just red the 1st number and mail below it i don't know what to do to read the 2nd and 3rd or any no. of mails from this file.
the code i have written is below will be really greatful for assisstance

#include <stdio.h>
main()
{
FILE * kp;
char classmain[100];
int i=0, j=0,x=0;
//flag f=0;
kp=fopen("sms","r");
//fread(classmain,0,10000,kp);
 
if(kp==NULL)
{
printf("unable to open the file");
exit(1);
}
while(!feof(kp))
{
while(fgets(classmain,100,kp) != NULL)
{
//fputs(classmain, stdout);
//printf("%s", classmain);
if (strstr(classmain,"Subject"))
//printf("%s", classmain);
break;
}
while(fgets(classmain,100,kp)!= NULL)
{
if(strcmp(classmain,"")!=0)
break;
}
fgets(classmain,100,kp);
printf("%s",classmain);
 
while(fgets(classmain,100,kp)!=NULL)
{
if(strcmp(classmain,"")==0)
break;
printf("%s",classmain);
}
while(fgets(classmain,100,kp) != NULL)
{
//fputs(classmain, stdout);
//printf("%s", classmain);
if (strstr(classmain,"Subject"))
printf("%s", classmain);
break;
}
 
}//end of 1st while
 
fclose(kp);
}

[AdrianH]

Please indent your code. I'm not going to do it for you and I won't look at it till it is.
It is just too hard to read.

Adrian

[shermeenz]

i have provided it in indented form but when it displays on web there aren't any indentation it is opening in indented form in edit mode kindly check that out

#include <stdio.h>
main()
{
   FILE * kp;
   char classmain[100];
   int i=0, j=0,x=0;
 
      kp=fopen("sms","r");
      if(kp==NULL)
      {
    printf("unable to open the file");
    exit(1);
      }
 
      while(!feof(kp))
      {
 
    while(fgets(classmain,100,kp) != NULL)
    {
    if (strstr(classmain,"Subject"))
    break;
    }
 
      while(fgets(classmain,100,kp)!= NULL)
      {
      if(strcmp(classmain,"")!=0)
      break;
      }
      fgets(classmain,100,kp);
      printf("%s",classmain);
 
        while(fgets(classmain,100,kp)!=NULL)
        {
        if(strcmp(classmain,"")==0)
        break;
        printf("%s",classmain);
        }
        while(fgets(classmain,100,kp) != NULL)
        {
        if (strstr(classmain,"Subject"))
        printf("%s", classmain);
        break;
        }
 
      }//end of 1st while
 
fclose(kp);
}//end of main

[AdrianH]

You have to use [code][/code] tags, with the first tag stating what language it is. For C, use [code=c], for C++ use [code=cpp].

Even in edit I had problems reading it. so I've run it through a programme called indent using -kr switch. This is what I got:

#include <stdio.h>
main()
{
    FILE *kp;
    char classmain[100];
    int i = 0, j = 0, x = 0;
 
    kp = fopen("sms", "r");
    if (kp == NULL) {
        printf("unable to open the file");
        exit(1);
    }
 
    while (!feof(kp)) {
 
        while (fgets(classmain, 100, kp) != NULL) {
            if (strstr(classmain, "Subject"))
                break;
        }
 
        while (fgets(classmain, 100, kp) != NULL) {
            if (strcmp(classmain, "") != 0)
                break;
        }
        fgets(classmain, 100, kp);
        printf("%s", classmain);
 
        while (fgets(classmain, 100, kp) != NULL) {
            if (strcmp(classmain, "") == 0)
                break;
            printf("%s", classmain);
        }
        while (fgets(classmain, 100, kp) != NULL) {
            if (strstr(classmain, "Subject"))
                printf("%s", classmain);
            break;
        }
 
    }                           //end of 1st while
 
    fclose(kp);
}                               //end of main

I find this much more readable. (except perhaps the colours. We are looking into changing them ;))

Please reply to this message and put comments for each loop telling me what you are trying to accomplish.


Adrian

[shermeenz]

i have made changes to the logic
the new code is

#include <stdio.h>
main()
{
FILE * kp;
char classmain[100];
int i=0, j=0, x=0;
kp=fopen("sms","r");
        //if no file read do the following     
        if(kp==NULL)
    {
    printf("unable to open the file");
    exit(1);
    }
        //else read the file 
    while(!feof(kp))
    {
            //read every string until find Subject in file and then break and move to next while
        while(fgets(classmain,100,kp) != NULL)
        {
        if (strstr(classmain,"Subject"))
        break;
        }
 
        while(fgets(classmain,100,kp)!= NULL)
        {
                //check for the blank lines writen after subject ignore spaces and read number and next two lines
        if(strcmp(classmain," ")==1)
        break;
        }
        if(feof(kp))
        break;
        printf("%s",classmain);
        printf("%s",(fgets(classmain,100,kp)));
        printf("%s",(fgets(classmain,100,kp)));
    }//end of 1st while
fclose(kp);
}
 

this code is working and giving me desired output but still have logical problems
if(strcmp(class main," ")==1)
in this condition i am comparing space with the string available in classmain while its not space its value in hex is 0a i checked the contents of my file using command
hexdump -C /sms
with what i should compare the string obtained?
do consider my file of mails with it and run this code and help me improving this thnx

[AdrianH]

i have made changes to the logic
the new code is

#include <stdio.h>
main()
{
FILE * kp;
char classmain[100];
int i=0, j=0, x=0;
kp=fopen("sms","r");
        //if no file read do the following     
        if(kp==NULL)
    {
    printf("unable to open the file");
    exit(1);
    }
        //else read the file 
    while(!feof(kp))
    {
            //read every string until find Subject in file and then break and move to next while
        while(fgets(classmain,100,kp) != NULL)
        {
        if (strstr(classmain,"Subject"))
        break;
        }
 
        while(fgets(classmain,100,kp)!= NULL)
        {
                //check for the blank lines writen after subject ignore spaces and read number and next two lines
        if(strcmp(classmain," ")==1)
        break;
        }
        if(feof(kp))
        break;
        printf("%s",classmain);
        printf("%s",(fgets(classmain,100,kp)));
        printf("%s",(fgets(classmain,100,kp)));
    }//end of 1st while
fclose(kp);
}
 

this code is working and giving me desired output but still have logical problems
if(strcmp(class main," ")==1)
in this condition i am comparing space with the string available in classmain while its not space its value in hex is 0a i checked the contents of my file using command
hexdump -C /sms
with what i should compare the string obtained?
do consider my file of mails with it and run this code and help me improving this thnx

Look up strcmp() here. Or for comparing a single char, classmain[0] == ' ' would work too.


Adrian